From f4ae2faa40199b97b12f508234640bc565d166f8 Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Wed, 11 Aug 2010 14:07:01 +0300 Subject: fix reiserfs_evict_inode end_writeback second call reiserfs_evict_inode calls end_writeback two times hitting kernel BUG at fs/inode.c:298 becase inode->i_state is I_CLEAR already. Signed-off-by: Sergey Senozhatsky Signed-off-by: Al Viro diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c index ae35413..caa7583 100644 --- a/fs/reiserfs/inode.c +++ b/fs/reiserfs/inode.c @@ -83,6 +83,7 @@ void reiserfs_evict_inode(struct inode *inode) dquot_drop(inode); inode->i_blocks = 0; reiserfs_write_unlock_once(inode->i_sb, depth); + return; no_delete: end_writeback(inode); -- cgit v0.10.2 From b845ff8f3ea2988ad5041315e2d35298e85cbc2f Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Tue, 17 Aug 2010 17:08:35 +0300 Subject: cramfs: only unlock new inodes Commit 77b8a75f5bb introduced a warning at fs/inode.c:692 unlock_new_inode(), caused by unlock_new_inode() being called on existing inodes as well. This patch changes setup_inode() to only call unlock_new_inode() for I_NEW inodes. Signed-off-by: Alexander Shishkin Signed-off-by: Al Viro diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index a53b130..1e7a330 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -80,7 +80,7 @@ static struct inode *get_cramfs_inode(struct super_block *sb, } } else { inode = iget_locked(sb, CRAMINO(cramfs_inode)); - if (inode) { + if (inode && (inode->i_state & I_NEW)) { setup_inode(inode, cramfs_inode); unlock_new_inode(inode); } -- cgit v0.10.2 From dad5eb6daa7eeb63d4fc9d982892c59faa07e797 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 17 Aug 2010 12:42:13 +0200 Subject: vfs: update ctime when changing the file's permission by setfacl generic_acl_set didn't update the ctime of the file when its permission was changed. Steps to reproduce: # touch aaa # stat -c %Z aaa 1275289822 # setfacl -m 'u::x,g::x,o::x' aaa # stat -c %Z aaa 1275289822 <- unchanged But, according to the spec of the ctime, vfs must update it. Port of ext3 patch by Miao Xie . CC: Al Viro Signed-off-by: Jan Kara Signed-off-by: Al Viro diff --git a/fs/generic_acl.c b/fs/generic_acl.c index 99800e5..6bc9e3a 100644 --- a/fs/generic_acl.c +++ b/fs/generic_acl.c @@ -94,6 +94,7 @@ generic_acl_set(struct dentry *dentry, const char *name, const void *value, if (error < 0) goto failed; inode->i_mode = mode; + inode->i_ctime = CURRENT_TIME; if (error == 0) { posix_acl_release(acl); acl = NULL; -- cgit v0.10.2 From 87e99511ea54510ffb60b98001d108794d5037f8 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 11 Aug 2010 17:05:45 +0200 Subject: kill BH_Ordered flag Instead of abusing a buffer_head flag just add a variant of sync_dirty_buffer which allows passing the exact type of write flag required. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro diff --git a/fs/buffer.c b/fs/buffer.c index 50efa33..6c8ad97 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2912,13 +2912,6 @@ int submit_bh(int rw, struct buffer_head * bh) BUG_ON(buffer_unwritten(bh)); /* - * Mask in barrier bit for a write (could be either a WRITE or a - * WRITE_SYNC - */ - if (buffer_ordered(bh) && (rw & WRITE)) - rw |= WRITE_BARRIER; - - /* * Only clear out a write error when rewriting */ if (test_set_buffer_req(bh) && (rw & WRITE)) @@ -3021,7 +3014,7 @@ EXPORT_SYMBOL(ll_rw_block); * and then start new I/O and then wait upon it. The caller must have a ref on * the buffer_head. */ -int sync_dirty_buffer(struct buffer_head *bh) +int __sync_dirty_buffer(struct buffer_head *bh, int rw) { int ret = 0; @@ -3030,7 +3023,7 @@ int sync_dirty_buffer(struct buffer_head *bh) if (test_clear_buffer_dirty(bh)) { get_bh(bh); bh->b_end_io = end_buffer_write_sync; - ret = submit_bh(WRITE_SYNC, bh); + ret = submit_bh(rw, bh); wait_on_buffer(bh); if (buffer_eopnotsupp(bh)) { clear_buffer_eopnotsupp(bh); @@ -3043,6 +3036,12 @@ int sync_dirty_buffer(struct buffer_head *bh) } return ret; } +EXPORT_SYMBOL(__sync_dirty_buffer); + +int sync_dirty_buffer(struct buffer_head *bh) +{ + return __sync_dirty_buffer(bh, WRITE_SYNC); +} EXPORT_SYMBOL(sync_dirty_buffer); /* diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c index 28a9dda..95d8c11 100644 --- a/fs/jbd/commit.c +++ b/fs/jbd/commit.c @@ -119,7 +119,6 @@ static int journal_write_commit_record(journal_t *journal, struct buffer_head *bh; journal_header_t *header; int ret; - int barrier_done = 0; if (is_journal_aborted(journal)) return 0; @@ -137,34 +136,36 @@ static int journal_write_commit_record(journal_t *journal, JBUFFER_TRACE(descriptor, "write commit block"); set_buffer_dirty(bh); + if (journal->j_flags & JFS_BARRIER) { - set_buffer_ordered(bh); - barrier_done = 1; - } - ret = sync_dirty_buffer(bh); - if (barrier_done) - clear_buffer_ordered(bh); - /* is it possible for another commit to fail at roughly - * the same time as this one? If so, we don't want to - * trust the barrier flag in the super, but instead want - * to remember if we sent a barrier request - */ - if (ret == -EOPNOTSUPP && barrier_done) { - char b[BDEVNAME_SIZE]; + ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_BARRIER); - printk(KERN_WARNING - "JBD: barrier-based sync failed on %s - " - "disabling barriers\n", - bdevname(journal->j_dev, b)); - spin_lock(&journal->j_state_lock); - journal->j_flags &= ~JFS_BARRIER; - spin_unlock(&journal->j_state_lock); + /* + * Is it possible for another commit to fail at roughly + * the same time as this one? If so, we don't want to + * trust the barrier flag in the super, but instead want + * to remember if we sent a barrier request + */ + if (ret == -EOPNOTSUPP) { + char b[BDEVNAME_SIZE]; - /* And try again, without the barrier */ - set_buffer_uptodate(bh); - set_buffer_dirty(bh); + printk(KERN_WARNING + "JBD: barrier-based sync failed on %s - " + "disabling barriers\n", + bdevname(journal->j_dev, b)); + spin_lock(&journal->j_state_lock); + journal->j_flags &= ~JFS_BARRIER; + spin_unlock(&journal->j_state_lock); + + /* And try again, without the barrier */ + set_buffer_uptodate(bh); + set_buffer_dirty(bh); + ret = sync_dirty_buffer(bh); + } + } else { ret = sync_dirty_buffer(bh); } + put_bh(bh); /* One for getblk() */ journal_put_journal_head(descriptor); diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index f52e5e8..7c068c1 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -101,7 +101,6 @@ static int journal_submit_commit_record(journal_t *journal, struct commit_header *tmp; struct buffer_head *bh; int ret; - int barrier_done = 0; struct timespec now = current_kernel_time(); if (is_journal_aborted(journal)) @@ -136,30 +135,22 @@ static int journal_submit_commit_record(journal_t *journal, if (journal->j_flags & JBD2_BARRIER && !JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { - set_buffer_ordered(bh); - barrier_done = 1; - } - ret = submit_bh(WRITE_SYNC_PLUG, bh); - if (barrier_done) - clear_buffer_ordered(bh); - - /* is it possible for another commit to fail at roughly - * the same time as this one? If so, we don't want to - * trust the barrier flag in the super, but instead want - * to remember if we sent a barrier request - */ - if (ret == -EOPNOTSUPP && barrier_done) { - printk(KERN_WARNING - "JBD2: Disabling barriers on %s, " - "not supported by device\n", journal->j_devname); - write_lock(&journal->j_state_lock); - journal->j_flags &= ~JBD2_BARRIER; - write_unlock(&journal->j_state_lock); + ret = submit_bh(WRITE_SYNC_PLUG | WRITE_BARRIER, bh); + if (ret == -EOPNOTSUPP) { + printk(KERN_WARNING + "JBD2: Disabling barriers on %s, " + "not supported by device\n", journal->j_devname); + write_lock(&journal->j_state_lock); + journal->j_flags &= ~JBD2_BARRIER; + write_unlock(&journal->j_state_lock); - /* And try again, without the barrier */ - lock_buffer(bh); - set_buffer_uptodate(bh); - clear_buffer_dirty(bh); + /* And try again, without the barrier */ + lock_buffer(bh); + set_buffer_uptodate(bh); + clear_buffer_dirty(bh); + ret = submit_bh(WRITE_SYNC_PLUG, bh); + } + } else { ret = submit_bh(WRITE_SYNC_PLUG, bh); } *cbh = bh; diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index 1fa86b9..6834543 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -175,24 +175,24 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int flag) { struct the_nilfs *nilfs = sbi->s_nilfs; int err; - int barrier_done = 0; - if (nilfs_test_opt(sbi, BARRIER)) { - set_buffer_ordered(nilfs->ns_sbh[0]); - barrier_done = 1; - } retry: set_buffer_dirty(nilfs->ns_sbh[0]); - err = sync_dirty_buffer(nilfs->ns_sbh[0]); - if (err == -EOPNOTSUPP && barrier_done) { - nilfs_warning(sbi->s_super, __func__, - "barrier-based sync failed. " - "disabling barriers\n"); - nilfs_clear_opt(sbi, BARRIER); - barrier_done = 0; - clear_buffer_ordered(nilfs->ns_sbh[0]); - goto retry; + + if (nilfs_test_opt(sbi, BARRIER)) { + err = __sync_dirty_buffer(nilfs->ns_sbh[0], + WRITE_SYNC | WRITE_BARRIER); + if (err == -EOPNOTSUPP) { + nilfs_warning(sbi->s_super, __func__, + "barrier-based sync failed. " + "disabling barriers\n"); + nilfs_clear_opt(sbi, BARRIER); + goto retry; + } + } else { + err = sync_dirty_buffer(nilfs->ns_sbh[0]); } + if (unlikely(err)) { printk(KERN_ERR "NILFS: unable to write superblock (err=%d)\n", err); diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 43e649a..72c1cf8 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -32,7 +32,6 @@ enum bh_state_bits { BH_Delay, /* Buffer is not yet allocated on disk */ BH_Boundary, /* Block is followed by a discontiguity */ BH_Write_EIO, /* I/O error on write */ - BH_Ordered, /* ordered write */ BH_Eopnotsupp, /* operation not supported (barrier) */ BH_Unwritten, /* Buffer is allocated on disk but not written */ BH_Quiet, /* Buffer Error Prinks to be quiet */ @@ -125,7 +124,6 @@ BUFFER_FNS(Async_Write, async_write) BUFFER_FNS(Delay, delay) BUFFER_FNS(Boundary, boundary) BUFFER_FNS(Write_EIO, write_io_error) -BUFFER_FNS(Ordered, ordered) BUFFER_FNS(Eopnotsupp, eopnotsupp) BUFFER_FNS(Unwritten, unwritten) @@ -183,6 +181,7 @@ void unlock_buffer(struct buffer_head *bh); void __lock_buffer(struct buffer_head *bh); void ll_rw_block(int, int, struct buffer_head * bh[]); int sync_dirty_buffer(struct buffer_head *bh); +int __sync_dirty_buffer(struct buffer_head *bh, int rw); int submit_bh(int, struct buffer_head *); void write_boundary_block(struct block_device *bdev, sector_t bblock, unsigned blocksize); -- cgit v0.10.2 From 9cb569d601e0b93e01c20a22872270ec663b75f6 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 11 Aug 2010 17:06:24 +0200 Subject: remove SWRITE* I/O types These flags aren't real I/O types, but tell ll_rw_block to always lock the buffer instead of giving up on a failed trylock. Instead add a new write_dirty_buffer helper that implements this semantic and use it from the existing SWRITE* callers. Note that the ll_rw_block code had a bug where it didn't promote WRITE_SYNC_PLUG properly, which this patch fixes. In the ufs code clean up the helper that used to call ll_rw_block to mirror sync_dirty_buffer, which is the function it implements for compound buffers. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro diff --git a/fs/buffer.c b/fs/buffer.c index 6c8ad97..3e7dca2 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -770,11 +770,12 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) spin_unlock(lock); /* * Ensure any pending I/O completes so that - * ll_rw_block() actually writes the current - * contents - it is a noop if I/O is still in - * flight on potentially older contents. + * write_dirty_buffer() actually writes the + * current contents - it is a noop if I/O is + * still in flight on potentially older + * contents. */ - ll_rw_block(SWRITE_SYNC_PLUG, 1, &bh); + write_dirty_buffer(bh, WRITE_SYNC_PLUG); /* * Kick off IO for the previous mapping. Note @@ -2949,22 +2950,21 @@ EXPORT_SYMBOL(submit_bh); /** * ll_rw_block: low-level access to block devices (DEPRECATED) - * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) + * @rw: whether to %READ or %WRITE or maybe %READA (readahead) * @nr: number of &struct buffer_heads in the array * @bhs: array of pointers to &struct buffer_head * * ll_rw_block() takes an array of pointers to &struct buffer_heads, and * requests an I/O operation on them, either a %READ or a %WRITE. The third - * %SWRITE is like %WRITE only we make sure that the *current* data in buffers - * are sent to disk. The fourth %READA option is described in the documentation - * for generic_make_request() which ll_rw_block() calls. + * %READA option is described in the documentation for generic_make_request() + * which ll_rw_block() calls. * * This function drops any buffer that it cannot get a lock on (with the - * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be - * clean when doing a write request, and any buffer that appears to be - * up-to-date when doing read request. Further it marks as clean buffers that - * are processed for writing (the buffer cache won't assume that they are - * actually clean until the buffer gets unlocked). + * BH_Lock state bit), any buffer that appears to be clean when doing a write + * request, and any buffer that appears to be up-to-date when doing read + * request. Further it marks as clean buffers that are processed for + * writing (the buffer cache won't assume that they are actually clean + * until the buffer gets unlocked). * * ll_rw_block sets b_end_io to simple completion handler that marks * the buffer up-to-date (if approriate), unlocks the buffer and wakes @@ -2980,20 +2980,13 @@ void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) for (i = 0; i < nr; i++) { struct buffer_head *bh = bhs[i]; - if (rw == SWRITE || rw == SWRITE_SYNC || rw == SWRITE_SYNC_PLUG) - lock_buffer(bh); - else if (!trylock_buffer(bh)) + if (!trylock_buffer(bh)) continue; - - if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC || - rw == SWRITE_SYNC_PLUG) { + if (rw == WRITE) { if (test_clear_buffer_dirty(bh)) { bh->b_end_io = end_buffer_write_sync; get_bh(bh); - if (rw == SWRITE_SYNC) - submit_bh(WRITE_SYNC, bh); - else - submit_bh(WRITE, bh); + submit_bh(WRITE, bh); continue; } } else { @@ -3009,6 +3002,19 @@ void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) } EXPORT_SYMBOL(ll_rw_block); +void write_dirty_buffer(struct buffer_head *bh, int rw) +{ + lock_buffer(bh); + if (!test_clear_buffer_dirty(bh)) { + unlock_buffer(bh); + return; + } + bh->b_end_io = end_buffer_write_sync; + get_bh(bh); + submit_bh(rw, bh); +} +EXPORT_SYMBOL(write_dirty_buffer); + /* * For a data-integrity writeout, we need to wait upon any in-progress I/O * and then start new I/O and then wait upon it. The caller must have a ref on diff --git a/fs/fat/misc.c b/fs/fat/misc.c index 1fa23f6..1736f23 100644 --- a/fs/fat/misc.c +++ b/fs/fat/misc.c @@ -250,7 +250,9 @@ int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) { int i, err = 0; - ll_rw_block(SWRITE, nr_bhs, bhs); + for (i = 0; i < nr_bhs; i++) + write_dirty_buffer(bhs[i], WRITE); + for (i = 0; i < nr_bhs; i++) { wait_on_buffer(bhs[i]); if (buffer_eopnotsupp(bhs[i])) { diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c index b0435dd..05a38b9 100644 --- a/fs/jbd/checkpoint.c +++ b/fs/jbd/checkpoint.c @@ -254,7 +254,9 @@ __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) { int i; - ll_rw_block(SWRITE, *batch_count, bhs); + for (i = 0; i < *batch_count; i++) + write_dirty_buffer(bhs[i], WRITE); + for (i = 0; i < *batch_count; i++) { struct buffer_head *bh = bhs[i]; clear_buffer_jwrite(bh); diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c index f19ce94..2c4b1f1 100644 --- a/fs/jbd/journal.c +++ b/fs/jbd/journal.c @@ -1024,7 +1024,7 @@ void journal_update_superblock(journal_t *journal, int wait) if (wait) sync_dirty_buffer(bh); else - ll_rw_block(SWRITE, 1, &bh); + write_dirty_buffer(bh, WRITE); out: /* If we have just flushed the log (by marking s_start==0), then diff --git a/fs/jbd/revoke.c b/fs/jbd/revoke.c index ad71732..d290183 100644 --- a/fs/jbd/revoke.c +++ b/fs/jbd/revoke.c @@ -617,7 +617,7 @@ static void flush_descriptor(journal_t *journal, set_buffer_jwrite(bh); BUFFER_TRACE(bh, "write"); set_buffer_dirty(bh); - ll_rw_block((write_op == WRITE) ? SWRITE : SWRITE_SYNC_PLUG, 1, &bh); + write_dirty_buffer(bh, write_op); } #endif diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c index 1c23a0f..5247e7f 100644 --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -255,7 +255,9 @@ __flush_batch(journal_t *journal, int *batch_count) { int i; - ll_rw_block(SWRITE, *batch_count, journal->j_chkpt_bhs); + for (i = 0; i < *batch_count; i++) + write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE); + for (i = 0; i < *batch_count; i++) { struct buffer_head *bh = journal->j_chkpt_bhs[i]; clear_buffer_jwrite(bh); diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index ad5866a..0e8014e 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1124,7 +1124,7 @@ void jbd2_journal_update_superblock(journal_t *journal, int wait) set_buffer_uptodate(bh); } } else - ll_rw_block(SWRITE, 1, &bh); + write_dirty_buffer(bh, WRITE); out: /* If we have just flushed the log (by marking s_start==0), then diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c index a360b06..9ad321f 100644 --- a/fs/jbd2/revoke.c +++ b/fs/jbd2/revoke.c @@ -625,7 +625,7 @@ static void flush_descriptor(journal_t *journal, set_buffer_jwrite(bh); BUFFER_TRACE(bh, "write"); set_buffer_dirty(bh); - ll_rw_block((write_op == WRITE) ? SWRITE : SWRITE_SYNC_PLUG, 1, &bh); + write_dirty_buffer(bh, write_op); } #endif diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c index 1ec952b..812e2c0 100644 --- a/fs/reiserfs/journal.c +++ b/fs/reiserfs/journal.c @@ -2311,7 +2311,7 @@ static int journal_read_transaction(struct super_block *sb, /* flush out the real blocks */ for (i = 0; i < get_desc_trans_len(desc); i++) { set_buffer_dirty(real_blocks[i]); - ll_rw_block(SWRITE, 1, real_blocks + i); + write_dirty_buffer(real_blocks[i], WRITE); } for (i = 0; i < get_desc_trans_len(desc); i++) { wait_on_buffer(real_blocks[i]); diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c index 048484f..46f7a80 100644 --- a/fs/ufs/balloc.c +++ b/fs/ufs/balloc.c @@ -114,10 +114,8 @@ void ufs_free_fragments(struct inode *inode, u64 fragment, unsigned count) ubh_mark_buffer_dirty (USPI_UBH(uspi)); ubh_mark_buffer_dirty (UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer (UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); sb->s_dirt = 1; unlock_super (sb); @@ -207,10 +205,8 @@ do_more: ubh_mark_buffer_dirty (USPI_UBH(uspi)); ubh_mark_buffer_dirty (UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer (UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); if (overflow) { fragment += count; @@ -558,10 +554,8 @@ static u64 ufs_add_fragments(struct inode *inode, u64 fragment, ubh_mark_buffer_dirty (USPI_UBH(uspi)); ubh_mark_buffer_dirty (UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer (UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); sb->s_dirt = 1; UFSD("EXIT, fragment %llu\n", (unsigned long long)fragment); @@ -680,10 +674,8 @@ cg_found: succed: ubh_mark_buffer_dirty (USPI_UBH(uspi)); ubh_mark_buffer_dirty (UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer (UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); sb->s_dirt = 1; result += cgno * uspi->s_fpg; diff --git a/fs/ufs/ialloc.c b/fs/ufs/ialloc.c index 428017e..2eabf04 100644 --- a/fs/ufs/ialloc.c +++ b/fs/ufs/ialloc.c @@ -113,10 +113,8 @@ void ufs_free_inode (struct inode * inode) ubh_mark_buffer_dirty (USPI_UBH(uspi)); ubh_mark_buffer_dirty (UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer (UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); sb->s_dirt = 1; unlock_super (sb); @@ -156,10 +154,8 @@ static void ufs2_init_inodes_chunk(struct super_block *sb, fs32_add(sb, &ucg->cg_u.cg_u2.cg_initediblk, uspi->s_inopb); ubh_mark_buffer_dirty(UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer(UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); UFSD("EXIT\n"); } @@ -290,10 +286,8 @@ cg_found: } ubh_mark_buffer_dirty (USPI_UBH(uspi)); ubh_mark_buffer_dirty (UCPI_UBH(ucpi)); - if (sb->s_flags & MS_SYNCHRONOUS) { - ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi)); - ubh_wait_on_buffer (UCPI_UBH(ucpi)); - } + if (sb->s_flags & MS_SYNCHRONOUS) + ubh_sync_block(UCPI_UBH(ucpi)); sb->s_dirt = 1; inode->i_ino = cg * uspi->s_ipg + bit; diff --git a/fs/ufs/truncate.c b/fs/ufs/truncate.c index 34d5cb1..a58f915 100644 --- a/fs/ufs/truncate.c +++ b/fs/ufs/truncate.c @@ -243,10 +243,8 @@ static int ufs_trunc_indirect(struct inode *inode, u64 offset, void *p) ubh_bforget(ind_ubh); ind_ubh = NULL; } - if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh)) { - ubh_ll_rw_block(SWRITE, ind_ubh); - ubh_wait_on_buffer (ind_ubh); - } + if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh)) + ubh_sync_block(ind_ubh); ubh_brelse (ind_ubh); UFSD("EXIT: ino %lu\n", inode->i_ino); @@ -307,10 +305,8 @@ static int ufs_trunc_dindirect(struct inode *inode, u64 offset, void *p) ubh_bforget(dind_bh); dind_bh = NULL; } - if (IS_SYNC(inode) && dind_bh && ubh_buffer_dirty(dind_bh)) { - ubh_ll_rw_block(SWRITE, dind_bh); - ubh_wait_on_buffer (dind_bh); - } + if (IS_SYNC(inode) && dind_bh && ubh_buffer_dirty(dind_bh)) + ubh_sync_block(dind_bh); ubh_brelse (dind_bh); UFSD("EXIT: ino %lu\n", inode->i_ino); @@ -367,10 +363,8 @@ static int ufs_trunc_tindirect(struct inode *inode) ubh_bforget(tind_bh); tind_bh = NULL; } - if (IS_SYNC(inode) && tind_bh && ubh_buffer_dirty(tind_bh)) { - ubh_ll_rw_block(SWRITE, tind_bh); - ubh_wait_on_buffer (tind_bh); - } + if (IS_SYNC(inode) && tind_bh && ubh_buffer_dirty(tind_bh)) + ubh_sync_block(tind_bh); ubh_brelse (tind_bh); UFSD("EXIT: ino %lu\n", inode->i_ino); diff --git a/fs/ufs/util.c b/fs/ufs/util.c index 85a7fc9..d2c36d5 100644 --- a/fs/ufs/util.c +++ b/fs/ufs/util.c @@ -113,21 +113,17 @@ void ubh_mark_buffer_uptodate (struct ufs_buffer_head * ubh, int flag) } } -void ubh_ll_rw_block(int rw, struct ufs_buffer_head *ubh) +void ubh_sync_block(struct ufs_buffer_head *ubh) { - if (!ubh) - return; + if (ubh) { + unsigned i; - ll_rw_block(rw, ubh->count, ubh->bh); -} + for (i = 0; i < ubh->count; i++) + write_dirty_buffer(ubh->bh[i], WRITE); -void ubh_wait_on_buffer (struct ufs_buffer_head * ubh) -{ - unsigned i; - if (!ubh) - return; - for ( i = 0; i < ubh->count; i++ ) - wait_on_buffer (ubh->bh[i]); + for (i = 0; i < ubh->count; i++) + wait_on_buffer(ubh->bh[i]); + } } void ubh_bforget (struct ufs_buffer_head * ubh) diff --git a/fs/ufs/util.h b/fs/ufs/util.h index 0466036..9f8775c 100644 --- a/fs/ufs/util.h +++ b/fs/ufs/util.h @@ -269,8 +269,7 @@ extern void ubh_brelse (struct ufs_buffer_head *); extern void ubh_brelse_uspi (struct ufs_sb_private_info *); extern void ubh_mark_buffer_dirty (struct ufs_buffer_head *); extern void ubh_mark_buffer_uptodate (struct ufs_buffer_head *, int); -extern void ubh_ll_rw_block(int, struct ufs_buffer_head *); -extern void ubh_wait_on_buffer (struct ufs_buffer_head *); +extern void ubh_sync_block(struct ufs_buffer_head *); extern void ubh_bforget (struct ufs_buffer_head *); extern int ubh_buffer_dirty (struct ufs_buffer_head *); #define ubh_ubhcpymem(mem,ubh,size) _ubh_ubhcpymem_(uspi,mem,ubh,size) diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 72c1cf8..ec94c12 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -182,6 +182,7 @@ void __lock_buffer(struct buffer_head *bh); void ll_rw_block(int, int, struct buffer_head * bh[]); int sync_dirty_buffer(struct buffer_head *bh); int __sync_dirty_buffer(struct buffer_head *bh, int rw); +void write_dirty_buffer(struct buffer_head *bh, int rw); int submit_bh(int, struct buffer_head *); void write_boundary_block(struct block_device *bdev, sector_t bblock, unsigned blocksize); diff --git a/include/linux/fs.h b/include/linux/fs.h index 9a96b4d..29f7c97 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -125,9 +125,6 @@ struct inodes_stat_t { * block layer could (in theory) choose to ignore this * request if it runs into resource problems. * WRITE A normal async write. Device will be plugged. - * SWRITE Like WRITE, but a special case for ll_rw_block() that - * tells it to lock the buffer first. Normally a buffer - * must be locked before doing IO. * WRITE_SYNC_PLUG Synchronous write. Identical to WRITE, but passes down * the hint that someone will be waiting on this IO * shortly. The device must still be unplugged explicitly, @@ -138,9 +135,6 @@ struct inodes_stat_t { * immediately after submission. The write equivalent * of READ_SYNC. * WRITE_ODIRECT_PLUG Special case write for O_DIRECT only. - * SWRITE_SYNC - * SWRITE_SYNC_PLUG Like WRITE_SYNC/WRITE_SYNC_PLUG, but locks the buffer. - * See SWRITE. * WRITE_BARRIER Like WRITE_SYNC, but tells the block layer that all * previously submitted writes must be safely on storage * before this one is started. Also guarantees that when @@ -155,7 +149,6 @@ struct inodes_stat_t { #define READ 0 #define WRITE RW_MASK #define READA RWA_MASK -#define SWRITE (WRITE | READA) #define READ_SYNC (READ | REQ_SYNC | REQ_UNPLUG) #define READ_META (READ | REQ_META) @@ -165,8 +158,6 @@ struct inodes_stat_t { #define WRITE_META (WRITE | REQ_META) #define WRITE_BARRIER (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \ REQ_HARDBARRIER) -#define SWRITE_SYNC_PLUG (SWRITE | REQ_SYNC | REQ_NOIDLE) -#define SWRITE_SYNC (SWRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG) /* * These aren't really reads or writes, they pass down information about -- cgit v0.10.2 From 850a496f969719b494cc972ab1d0e088737358d7 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 18 Aug 2010 06:18:57 -0400 Subject: hostfs: dumb (and usually harmless) tpyo - strncpy instead of strlcpy ... not harmless in this case - we have a string in the end of buffer already. Signed-off-by: Al Viro diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index dd1e555..77c4f6e 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -104,7 +104,7 @@ static char *__dentry_name(struct dentry *dentry, char *name) __putname(name); return NULL; } - strncpy(name, root, PATH_MAX); + strlcpy(name, root, PATH_MAX); if (len > p - name) { __putname(name); return NULL; -- cgit v0.10.2 From 3b6036d148bad5bb7928b021a49bb9e395361084 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 18 Aug 2010 06:21:10 -0400 Subject: hostfs ->follow_link() braino we want the assignment to err done inside the if () to be visible after it, so (re)declaring err inside if () body is wrong. Signed-off-by: Al Viro diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index 77c4f6e..f7dc9b5 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -876,7 +876,7 @@ static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) char *path = dentry_name(dentry); int err = -ENOMEM; if (path) { - int err = hostfs_do_readlink(path, link, PATH_MAX); + err = hostfs_do_readlink(path, link, PATH_MAX); if (err == PATH_MAX) err = -E2BIG; __putname(path); -- cgit v0.10.2 From 3a48ee8a4ad26c3a538b6fc11a86a8f80c3dce18 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Mon, 16 Aug 2010 19:05:23 +0200 Subject: mbcache: Limit the maximum number of cache entries Limit the maximum number of mb_cache entries depending on the number of hash buckets: if the only limit to the number of cache entries is the available memory the hash chains can grow very long, taking a long time to search. At least partially solves https://bugzilla.lustre.org/show_bug.cgi?id=22771. Signed-off-by: Andreas Gruenbacher Signed-off-by: Al Viro diff --git a/fs/mbcache.c b/fs/mbcache.c index cf4e6cd..9344474 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -80,6 +80,7 @@ struct mb_cache { struct list_head c_cache_list; const char *c_name; atomic_t c_entry_count; + int c_max_entries; int c_bucket_bits; struct kmem_cache *c_entry_cache; struct list_head *c_block_hash; @@ -243,6 +244,12 @@ mb_cache_create(const char *name, int bucket_bits) if (!cache->c_entry_cache) goto fail2; + /* + * Set an upper limit on the number of cache entries so that the hash + * chains won't grow too long. + */ + cache->c_max_entries = bucket_count << 4; + spin_lock(&mb_cache_spinlock); list_add(&cache->c_cache_list, &mb_cache_list); spin_unlock(&mb_cache_spinlock); @@ -333,7 +340,6 @@ mb_cache_destroy(struct mb_cache *cache) kfree(cache); } - /* * mb_cache_entry_alloc() * @@ -345,17 +351,29 @@ mb_cache_destroy(struct mb_cache *cache) struct mb_cache_entry * mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags) { - struct mb_cache_entry *ce; - - ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags); - if (ce) { + struct mb_cache_entry *ce = NULL; + + if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) { + spin_lock(&mb_cache_spinlock); + if (!list_empty(&mb_cache_lru_list)) { + ce = list_entry(mb_cache_lru_list.next, + struct mb_cache_entry, e_lru_list); + list_del_init(&ce->e_lru_list); + __mb_cache_entry_unhash(ce); + } + spin_unlock(&mb_cache_spinlock); + } + if (!ce) { + ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags); + if (!ce) + return NULL; atomic_inc(&cache->c_entry_count); INIT_LIST_HEAD(&ce->e_lru_list); INIT_LIST_HEAD(&ce->e_block_list); ce->e_cache = cache; - ce->e_used = 1 + MB_CACHE_WRITER; ce->e_queued = 0; } + ce->e_used = 1 + MB_CACHE_WRITER; return ce; } -- cgit v0.10.2 From 2e2e88ea8c3bd9e1bd6e42faf047a4ac3fbb3b2f Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:30 +1000 Subject: fs: fix do_lookup false negative fs: fix do_lookup false negative In do_lookup, if we initially find no dentry, we take the directory i_mutex and re-check the lookup. If we find a dentry there, then we revalidate it if needed. However if that revalidate asks for the dentry to be invalidated, we return -ENOENT from do_lookup. What should happen instead is an attempt to allocate and lookup a new dentry. This is probably not noticed because it is rare. It is only reached if a concurrent create races in first (in which case, the dentry probably won't be invalidated anyway), or if the racy __d_lookup has failed due to a false-negative (which is very rare). Fix this by removing code and have it use the normal reval path. Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/fs/namei.c b/fs/namei.c index 17ea76bf..c2742b7 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -709,6 +709,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, dentry = __d_lookup(nd->path.dentry, name); if (!dentry) goto need_lookup; +found: if (dentry->d_op && dentry->d_op->d_revalidate) goto need_revalidate; done: @@ -766,14 +767,7 @@ out_unlock: * we waited on the semaphore. Need to revalidate. */ mutex_unlock(&dir->i_mutex); - if (dentry->d_op && dentry->d_op->d_revalidate) { - dentry = do_revalidate(dentry, nd); - if (!dentry) - dentry = ERR_PTR(-ENOENT); - } - if (IS_ERR(dentry)) - goto fail; - goto done; + goto found; need_revalidate: dentry = do_revalidate(dentry, nd); -- cgit v0.10.2 From baa0389073eb7beb9d36f6d13df97e16c1bfa626 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:31 +1000 Subject: fs: dentry allocation consolidation fs: dentry allocation consolidation There are 2 duplicate copies of code in dentry allocation in path lookup. Consolidate them into a single function. Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/fs/namei.c b/fs/namei.c index c2742b7..b815a4d 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -686,6 +686,35 @@ static __always_inline void follow_dotdot(struct nameidata *nd) } /* + * Allocate a dentry with name and parent, and perform a parent + * directory ->lookup on it. Returns the new dentry, or ERR_PTR + * on error. parent->d_inode->i_mutex must be held. d_lookup must + * have verified that no child exists while under i_mutex. + */ +static struct dentry *d_alloc_and_lookup(struct dentry *parent, + struct qstr *name, struct nameidata *nd) +{ + struct inode *inode = parent->d_inode; + struct dentry *dentry; + struct dentry *old; + + /* Don't create child dentry for a dead directory. */ + if (unlikely(IS_DEADDIR(inode))) + return ERR_PTR(-ENOENT); + + dentry = d_alloc(parent, name); + if (unlikely(!dentry)) + return ERR_PTR(-ENOMEM); + + old = inode->i_op->lookup(inode, dentry, nd); + if (unlikely(old)) { + dput(dentry); + dentry = old; + } + return dentry; +} + +/* * It's more convoluted than I'd like it to be, but... it's still fairly * small and for now I'd prefer to have fast path as straight as possible. * It _is_ time-critical. @@ -738,30 +767,13 @@ need_lookup: * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup */ dentry = d_lookup(parent, name); - if (!dentry) { - struct dentry *new; - - /* Don't create child dentry for a dead directory. */ - dentry = ERR_PTR(-ENOENT); - if (IS_DEADDIR(dir)) - goto out_unlock; - - new = d_alloc(parent, name); - dentry = ERR_PTR(-ENOMEM); - if (new) { - dentry = dir->i_op->lookup(dir, new, nd); - if (dentry) - dput(new); - else - dentry = new; - } -out_unlock: + if (likely(!dentry)) { + dentry = d_alloc_and_lookup(parent, name, nd); mutex_unlock(&dir->i_mutex); if (IS_ERR(dentry)) goto fail; goto done; } - /* * Uhhuh! Nasty case: the cache was re-populated while * we waited on the semaphore. Need to revalidate. @@ -1135,24 +1147,8 @@ static struct dentry *__lookup_hash(struct qstr *name, if (dentry && dentry->d_op && dentry->d_op->d_revalidate) dentry = do_revalidate(dentry, nd); - if (!dentry) { - struct dentry *new; - - /* Don't create child dentry for a dead directory. */ - dentry = ERR_PTR(-ENOENT); - if (IS_DEADDIR(inode)) - goto out; - - new = d_alloc(base, name); - dentry = ERR_PTR(-ENOMEM); - if (!new) - goto out; - dentry = inode->i_op->lookup(inode, new, nd); - if (!dentry) - dentry = new; - else - dput(new); - } + if (!dentry) + dentry = d_alloc_and_lookup(base, name, nd); out: return dentry; } -- cgit v0.10.2 From 44672e4fbd40e2dda8bbce7d0f71d24dbfc7e00e Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:32 +1000 Subject: apparmor: use task path helpers apparmor: use task path helpers Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/security/apparmor/path.c b/security/apparmor/path.c index 96bab94..19358dc 100644 --- a/security/apparmor/path.c +++ b/security/apparmor/path.c @@ -62,19 +62,14 @@ static int d_namespace_path(struct path *path, char *buf, int buflen, int deleted, connected; int error = 0; - /* Get the root we want to resolve too */ + /* Get the root we want to resolve too, released below */ if (flags & PATH_CHROOT_REL) { /* resolve paths relative to chroot */ - read_lock(¤t->fs->lock); - root = current->fs->root; - /* released below */ - path_get(&root); - read_unlock(¤t->fs->lock); + get_fs_root(current->fs, &root); } else { /* resolve paths relative to namespace */ root.mnt = current->nsproxy->mnt_ns->root; root.dentry = root.mnt->mnt_root; - /* released below */ path_get(&root); } -- cgit v0.10.2 From 2a4419b5b2a77f3f4537c14f7ad7df95770655dd Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:33 +1000 Subject: fs: fs_struct rwlock to spinlock fs: fs_struct rwlock to spinlock struct fs_struct.lock is an rwlock with the read-side used to protect root and pwd members while taking references to them. Taking a reference to a path typically requires just 2 atomic ops, so the critical section is very small. Parallel read-side operations would have cacheline contention on the lock, the dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a real parallelism increase. Replace it with a spinlock to avoid one or two atomic operations in typical path lookup fastpath. Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/drivers/staging/pohmelfs/path_entry.c b/drivers/staging/pohmelfs/path_entry.c index cdc4dd5..8ec83d2 100644 --- a/drivers/staging/pohmelfs/path_entry.c +++ b/drivers/staging/pohmelfs/path_entry.c @@ -44,9 +44,9 @@ int pohmelfs_construct_path_string(struct pohmelfs_inode *pi, void *data, int le return -ENOENT; } - read_lock(¤t->fs->lock); + spin_lock(¤t->fs->lock); path.mnt = mntget(current->fs->root.mnt); - read_unlock(¤t->fs->lock); + spin_unlock(¤t->fs->lock); path.dentry = d; @@ -91,9 +91,9 @@ int pohmelfs_path_length(struct pohmelfs_inode *pi) return -ENOENT; } - read_lock(¤t->fs->lock); + spin_lock(¤t->fs->lock); root = dget(current->fs->root.dentry); - read_unlock(¤t->fs->lock); + spin_unlock(¤t->fs->lock); spin_lock(&dcache_lock); diff --git a/fs/exec.c b/fs/exec.c index 7761837..5adab2c 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1117,7 +1117,7 @@ int check_unsafe_exec(struct linux_binprm *bprm) bprm->unsafe = tracehook_unsafe_exec(p); n_fs = 1; - write_lock(&p->fs->lock); + spin_lock(&p->fs->lock); rcu_read_lock(); for (t = next_thread(p); t != p; t = next_thread(t)) { if (t->fs == p->fs) @@ -1134,7 +1134,7 @@ int check_unsafe_exec(struct linux_binprm *bprm) res = 1; } } - write_unlock(&p->fs->lock); + spin_unlock(&p->fs->lock); return res; } diff --git a/fs/fs_struct.c b/fs/fs_struct.c index 1ee40eb..ed45a9c 100644 --- a/fs/fs_struct.c +++ b/fs/fs_struct.c @@ -13,11 +13,11 @@ void set_fs_root(struct fs_struct *fs, struct path *path) { struct path old_root; - write_lock(&fs->lock); + spin_lock(&fs->lock); old_root = fs->root; fs->root = *path; path_get(path); - write_unlock(&fs->lock); + spin_unlock(&fs->lock); if (old_root.dentry) path_put(&old_root); } @@ -30,11 +30,11 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path) { struct path old_pwd; - write_lock(&fs->lock); + spin_lock(&fs->lock); old_pwd = fs->pwd; fs->pwd = *path; path_get(path); - write_unlock(&fs->lock); + spin_unlock(&fs->lock); if (old_pwd.dentry) path_put(&old_pwd); @@ -51,7 +51,7 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root) task_lock(p); fs = p->fs; if (fs) { - write_lock(&fs->lock); + spin_lock(&fs->lock); if (fs->root.dentry == old_root->dentry && fs->root.mnt == old_root->mnt) { path_get(new_root); @@ -64,7 +64,7 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root) fs->pwd = *new_root; count++; } - write_unlock(&fs->lock); + spin_unlock(&fs->lock); } task_unlock(p); } while_each_thread(g, p); @@ -87,10 +87,10 @@ void exit_fs(struct task_struct *tsk) if (fs) { int kill; task_lock(tsk); - write_lock(&fs->lock); + spin_lock(&fs->lock); tsk->fs = NULL; kill = !--fs->users; - write_unlock(&fs->lock); + spin_unlock(&fs->lock); task_unlock(tsk); if (kill) free_fs_struct(fs); @@ -104,7 +104,7 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old) if (fs) { fs->users = 1; fs->in_exec = 0; - rwlock_init(&fs->lock); + spin_lock_init(&fs->lock); fs->umask = old->umask; get_fs_root_and_pwd(old, &fs->root, &fs->pwd); } @@ -121,10 +121,10 @@ int unshare_fs_struct(void) return -ENOMEM; task_lock(current); - write_lock(&fs->lock); + spin_lock(&fs->lock); kill = !--fs->users; current->fs = new_fs; - write_unlock(&fs->lock); + spin_unlock(&fs->lock); task_unlock(current); if (kill) @@ -143,7 +143,7 @@ EXPORT_SYMBOL(current_umask); /* to be mentioned only in INIT_TASK */ struct fs_struct init_fs = { .users = 1, - .lock = __RW_LOCK_UNLOCKED(init_fs.lock), + .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock), .umask = 0022, }; @@ -156,14 +156,14 @@ void daemonize_fs_struct(void) task_lock(current); - write_lock(&init_fs.lock); + spin_lock(&init_fs.lock); init_fs.users++; - write_unlock(&init_fs.lock); + spin_unlock(&init_fs.lock); - write_lock(&fs->lock); + spin_lock(&fs->lock); current->fs = &init_fs; kill = !--fs->users; - write_unlock(&fs->lock); + spin_unlock(&fs->lock); task_unlock(current); if (kill) diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h index eca3d52..a42b5bf 100644 --- a/include/linux/fs_struct.h +++ b/include/linux/fs_struct.h @@ -5,7 +5,7 @@ struct fs_struct { int users; - rwlock_t lock; + spinlock_t lock; int umask; int in_exec; struct path root, pwd; @@ -23,29 +23,29 @@ extern int unshare_fs_struct(void); static inline void get_fs_root(struct fs_struct *fs, struct path *root) { - read_lock(&fs->lock); + spin_lock(&fs->lock); *root = fs->root; path_get(root); - read_unlock(&fs->lock); + spin_unlock(&fs->lock); } static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd) { - read_lock(&fs->lock); + spin_lock(&fs->lock); *pwd = fs->pwd; path_get(pwd); - read_unlock(&fs->lock); + spin_unlock(&fs->lock); } static inline void get_fs_root_and_pwd(struct fs_struct *fs, struct path *root, struct path *pwd) { - read_lock(&fs->lock); + spin_lock(&fs->lock); *root = fs->root; path_get(root); *pwd = fs->pwd; path_get(pwd); - read_unlock(&fs->lock); + spin_unlock(&fs->lock); } #endif /* _LINUX_FS_STRUCT_H */ diff --git a/kernel/fork.c b/kernel/fork.c index 98b4508..856eac3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -752,13 +752,13 @@ static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) struct fs_struct *fs = current->fs; if (clone_flags & CLONE_FS) { /* tsk->fs is already what we want */ - write_lock(&fs->lock); + spin_lock(&fs->lock); if (fs->in_exec) { - write_unlock(&fs->lock); + spin_unlock(&fs->lock); return -EAGAIN; } fs->users++; - write_unlock(&fs->lock); + spin_unlock(&fs->lock); return 0; } tsk->fs = copy_fs_struct(fs); @@ -1676,13 +1676,13 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) if (new_fs) { fs = current->fs; - write_lock(&fs->lock); + spin_lock(&fs->lock); current->fs = new_fs; if (--fs->users) new_fs = NULL; else new_fs = fs; - write_unlock(&fs->lock); + spin_unlock(&fs->lock); } if (new_mm) { -- cgit v0.10.2 From b04f784e5d19ed58892833dae845738972cea260 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:34 +1000 Subject: fs: remove extra lookup in __lookup_hash fs: remove extra lookup in __lookup_hash Optimize lookup for create operations, where no dentry should often be common-case. In cases where it is not, such as unlink, the added overhead is much smaller than the removed. Also, move comments about __d_lookup racyness to the __d_lookup call site. d_lookup is intuitive; __d_lookup is what needs commenting. So in that same vein, add kerneldoc comments to __d_lookup and clean up some of the comments: - We are interested in how the RCU lookup works here, particularly with renames. Make that explicit, and point to the document where it is explained in more detail. - RCU is pretty standard now, and macros make implementations pretty mindless. If we want to know about RCU barrier details, we look in RCU code. - Delete some boring legacy comments because we don't care much about how the code used to work, more about the interesting parts of how it works now. So comments about lazy LRU may be interesting, but would better be done in the LRU or refcount management code. Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/fs/dcache.c b/fs/dcache.c index 4d13bf5..d56a40b 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1332,31 +1332,13 @@ EXPORT_SYMBOL(d_add_ci); * d_lookup - search for a dentry * @parent: parent dentry * @name: qstr of name we wish to find + * Returns: dentry, or NULL * - * Searches the children of the parent dentry for the name in question. If - * the dentry is found its reference count is incremented and the dentry - * is returned. The caller must use dput to free the entry when it has - * finished using it. %NULL is returned on failure. - * - * __d_lookup is dcache_lock free. The hash list is protected using RCU. - * Memory barriers are used while updating and doing lockless traversal. - * To avoid races with d_move while rename is happening, d_lock is used. - * - * Overflows in memcmp(), while d_move, are avoided by keeping the length - * and name pointer in one structure pointed by d_qstr. - * - * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while - * lookup is going on. - * - * The dentry unused LRU is not updated even if lookup finds the required dentry - * in there. It is updated in places such as prune_dcache, shrink_dcache_sb, - * select_parent and __dget_locked. This laziness saves lookup from dcache_lock - * acquisition. - * - * d_lookup() is protected against the concurrent renames in some unrelated - * directory using the seqlockt_t rename_lock. + * d_lookup searches the children of the parent dentry for the name in + * question. If the dentry is found its reference count is incremented and the + * dentry is returned. The caller must use dput to free the entry when it has + * finished using it. %NULL is returned if the dentry does not exist. */ - struct dentry * d_lookup(struct dentry * parent, struct qstr * name) { struct dentry * dentry = NULL; @@ -1372,6 +1354,21 @@ struct dentry * d_lookup(struct dentry * parent, struct qstr * name) } EXPORT_SYMBOL(d_lookup); +/* + * __d_lookup - search for a dentry (racy) + * @parent: parent dentry + * @name: qstr of name we wish to find + * Returns: dentry, or NULL + * + * __d_lookup is like d_lookup, however it may (rarely) return a + * false-negative result due to unrelated rename activity. + * + * __d_lookup is slightly faster by avoiding rename_lock read seqlock, + * however it must be used carefully, eg. with a following d_lookup in + * the case of failure. + * + * __d_lookup callers must be commented. + */ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) { unsigned int len = name->len; @@ -1382,6 +1379,19 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) struct hlist_node *node; struct dentry *dentry; + /* + * The hash list is protected using RCU. + * + * Take d_lock when comparing a candidate dentry, to avoid races + * with d_move(). + * + * It is possible that concurrent renames can mess up our list + * walk here and result in missing our dentry, resulting in the + * false-negative result. d_lookup() protects against concurrent + * renames using rename_lock seqlock. + * + * See Documentation/vfs/dcache-locking.txt for more details. + */ rcu_read_lock(); hlist_for_each_entry_rcu(dentry, node, head, d_hash) { @@ -1396,8 +1406,8 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) /* * Recheck the dentry after taking the lock - d_move may have - * changed things. Don't bother checking the hash because we're - * about to compare the whole name anyway. + * changed things. Don't bother checking the hash because + * we're about to compare the whole name anyway. */ if (dentry->d_parent != parent) goto next; diff --git a/fs/namei.c b/fs/namei.c index b815a4d..11de7c3 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -735,6 +735,11 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, return err; } + /* + * Rename seqlock is not required here because in the off chance + * of a false negative due to a concurrent rename, we're going to + * do the non-racy lookup, below. + */ dentry = __d_lookup(nd->path.dentry, name); if (!dentry) goto need_lookup; @@ -754,17 +759,13 @@ need_lookup: mutex_lock(&dir->i_mutex); /* * First re-do the cached lookup just in case it was created - * while we waited for the directory semaphore.. - * - * FIXME! This could use version numbering or similar to - * avoid unnecessary cache lookups. - * - * The "dcache_lock" is purely to protect the RCU list walker - * from concurrent renames at this point (we mustn't get false - * negatives from the RCU list walk here, unlike the optimistic - * fast walk). + * while we waited for the directory semaphore, or the first + * lookup failed due to an unrelated rename. * - * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup + * This could use version numbering or similar to avoid unnecessary + * cache lookups, but then we'd have to do the first lookup in the + * non-racy way. However in the common case here, everything should + * be hot in cache, so would it be a big win? */ dentry = d_lookup(parent, name); if (likely(!dentry)) { @@ -1136,13 +1137,12 @@ static struct dentry *__lookup_hash(struct qstr *name, goto out; } - dentry = __d_lookup(base, name); - - /* lockess __d_lookup may fail due to concurrent d_move() - * in some unrelated directory, so try with d_lookup + /* + * Don't bother with __d_lookup: callers are for creat as + * well as unlink, so a lot of the time it would cost + * a double lookup. */ - if (!dentry) - dentry = d_lookup(base, name); + dentry = d_lookup(base, name); if (dentry && dentry->d_op && dentry->d_op->d_revalidate) dentry = do_revalidate(dentry, nd); -- cgit v0.10.2 From ee2ffa0dfdd2db19705f2ba1c6a4c0bfe8122dd8 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:35 +1000 Subject: fs: cleanup files_lock locking fs: cleanup files_lock locking Lock tty_files with a new spinlock, tty_files_lock; provide helpers to manipulate the per-sb files list; unexport the files_lock spinlock. Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig Cc: Alan Cox Acked-by: Andi Kleen Acked-by: Greg Kroah-Hartman Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/drivers/char/pty.c b/drivers/char/pty.c index ad46eae..2c64faa 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -676,7 +676,11 @@ static int ptmx_open(struct inode *inode, struct file *filp) set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ filp->private_data = tty; - file_move(filp, &tty->tty_files); + + file_sb_list_del(filp); /* __dentry_open has put it on the sb list */ + spin_lock(&tty_files_lock); + list_add(&filp->f_u.fu_list, &tty->tty_files); + spin_unlock(&tty_files_lock); retval = devpts_pty_new(inode, tty->link); if (retval) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 0350c42..cd5b829 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -136,6 +136,9 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ DEFINE_MUTEX(tty_mutex); EXPORT_SYMBOL(tty_mutex); +/* Spinlock to protect the tty->tty_files list */ +DEFINE_SPINLOCK(tty_files_lock); + static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *); static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *); ssize_t redirected_tty_write(struct file *, const char __user *, @@ -235,11 +238,11 @@ static int check_tty_count(struct tty_struct *tty, const char *routine) struct list_head *p; int count = 0; - file_list_lock(); + spin_lock(&tty_files_lock); list_for_each(p, &tty->tty_files) { count++; } - file_list_unlock(); + spin_unlock(&tty_files_lock); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_SLAVE && tty->link && tty->link->count) @@ -519,7 +522,7 @@ void __tty_hangup(struct tty_struct *tty) workqueue with the lock held */ check_tty_count(tty, "tty_hangup"); - file_list_lock(); + spin_lock(&tty_files_lock); /* This breaks for file handles being sent over AF_UNIX sockets ? */ list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) { if (filp->f_op->write == redirected_tty_write) @@ -530,7 +533,7 @@ void __tty_hangup(struct tty_struct *tty) __tty_fasync(-1, filp, 0); /* can't block */ filp->f_op = &hung_up_tty_fops; } - file_list_unlock(); + spin_unlock(&tty_files_lock); tty_ldisc_hangup(tty); @@ -1424,9 +1427,9 @@ static void release_one_tty(struct work_struct *work) tty_driver_kref_put(driver); module_put(driver->owner); - file_list_lock(); + spin_lock(&tty_files_lock); list_del_init(&tty->tty_files); - file_list_unlock(); + spin_unlock(&tty_files_lock); put_pid(tty->pgrp); put_pid(tty->session); @@ -1671,7 +1674,10 @@ int tty_release(struct inode *inode, struct file *filp) * - do_tty_hangup no longer sees this file descriptor as * something that needs to be handled for hangups. */ - file_kill(filp); + spin_lock(&tty_files_lock); + BUG_ON(list_empty(&filp->f_u.fu_list)); + list_del_init(&filp->f_u.fu_list); + spin_unlock(&tty_files_lock); filp->private_data = NULL; /* @@ -1840,7 +1846,11 @@ got_driver: } filp->private_data = tty; - file_move(filp, &tty->tty_files); + BUG_ON(list_empty(&filp->f_u.fu_list)); + file_sb_list_del(filp); /* __dentry_open has put it on the sb list */ + spin_lock(&tty_files_lock); + list_add(&filp->f_u.fu_list, &tty->tty_files); + spin_unlock(&tty_files_lock); check_tty_count(tty, "tty_open"); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) diff --git a/fs/file_table.c b/fs/file_table.c index edecd36..6f0e62e 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -32,8 +32,7 @@ struct files_stat_struct files_stat = { .max_files = NR_FILE }; -/* public. Not pretty! */ -__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); /* SLAB cache for file structures */ static struct kmem_cache *filp_cachep __read_mostly; @@ -249,7 +248,7 @@ static void __fput(struct file *file) cdev_put(inode->i_cdev); fops_put(file->f_op); put_pid(file->f_owner.pid); - file_kill(file); + file_sb_list_del(file); if (file->f_mode & FMODE_WRITE) drop_file_write_access(file); file->f_path.dentry = NULL; @@ -328,31 +327,29 @@ struct file *fget_light(unsigned int fd, int *fput_needed) return file; } - void put_filp(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) { security_file_free(file); - file_kill(file); + file_sb_list_del(file); file_free(file); } } -void file_move(struct file *file, struct list_head *list) +void file_sb_list_add(struct file *file, struct super_block *sb) { - if (!list) - return; - file_list_lock(); - list_move(&file->f_u.fu_list, list); - file_list_unlock(); + spin_lock(&files_lock); + BUG_ON(!list_empty(&file->f_u.fu_list)); + list_add(&file->f_u.fu_list, &sb->s_files); + spin_unlock(&files_lock); } -void file_kill(struct file *file) +void file_sb_list_del(struct file *file) { if (!list_empty(&file->f_u.fu_list)) { - file_list_lock(); + spin_lock(&files_lock); list_del_init(&file->f_u.fu_list); - file_list_unlock(); + spin_unlock(&files_lock); } } @@ -361,7 +358,7 @@ int fs_may_remount_ro(struct super_block *sb) struct file *file; /* Check that no files are currently opened for writing. */ - file_list_lock(); + spin_lock(&files_lock); list_for_each_entry(file, &sb->s_files, f_u.fu_list) { struct inode *inode = file->f_path.dentry->d_inode; @@ -373,10 +370,10 @@ int fs_may_remount_ro(struct super_block *sb) if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) goto too_bad; } - file_list_unlock(); + spin_unlock(&files_lock); return 1; /* Tis' cool bro. */ too_bad: - file_list_unlock(); + spin_unlock(&files_lock); return 0; } @@ -392,7 +389,7 @@ void mark_files_ro(struct super_block *sb) struct file *f; retry: - file_list_lock(); + spin_lock(&files_lock); list_for_each_entry(f, &sb->s_files, f_u.fu_list) { struct vfsmount *mnt; if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) @@ -408,16 +405,13 @@ retry: continue; file_release_write(f); mnt = mntget(f->f_path.mnt); - file_list_unlock(); - /* - * This can sleep, so we can't hold - * the file_list_lock() spinlock. - */ + /* This can sleep, so we can't hold the spinlock. */ + spin_unlock(&files_lock); mnt_drop_write(mnt); mntput(mnt); goto retry; } - file_list_unlock(); + spin_unlock(&files_lock); } void __init files_init(unsigned long mempages) diff --git a/fs/open.c b/fs/open.c index 630715f..d74e198 100644 --- a/fs/open.c +++ b/fs/open.c @@ -675,7 +675,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, f->f_path.mnt = mnt; f->f_pos = 0; f->f_op = fops_get(inode->i_fop); - file_move(f, &inode->i_sb->s_files); + file_sb_list_add(f, inode->i_sb); error = security_dentry_open(f, cred); if (error) @@ -721,7 +721,7 @@ cleanup_all: mnt_drop_write(mnt); } } - file_kill(f); + file_sb_list_del(f); f->f_path.dentry = NULL; f->f_path.mnt = NULL; cleanup_file: diff --git a/include/linux/fs.h b/include/linux/fs.h index 29f7c97..5a9a9e5 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -944,9 +944,6 @@ struct file { unsigned long f_mnt_write_state; #endif }; -extern spinlock_t files_lock; -#define file_list_lock() spin_lock(&files_lock); -#define file_list_unlock() spin_unlock(&files_lock); #define get_file(x) atomic_long_inc(&(x)->f_count) #define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1) @@ -2188,8 +2185,8 @@ static inline void insert_inode_hash(struct inode *inode) { __insert_inode_hash(inode, inode->i_ino); } -extern void file_move(struct file *f, struct list_head *list); -extern void file_kill(struct file *f); +extern void file_sb_list_add(struct file *f, struct super_block *sb); +extern void file_sb_list_del(struct file *f); #ifdef CONFIG_BLOCK extern void submit_bio(int, struct bio *); extern int bdev_read_only(struct block_device *); diff --git a/include/linux/tty.h b/include/linux/tty.h index 1437da3..f6b371a 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -470,6 +470,7 @@ extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty); extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty); extern struct mutex tty_mutex; +extern spinlock_t tty_files_lock; extern void tty_write_unlock(struct tty_struct *tty); extern int tty_write_lock(struct tty_struct *tty, int ndelay); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 42043f9..bd7da0f 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2170,7 +2170,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, tty = get_current_tty(); if (tty) { - file_list_lock(); + spin_lock(&tty_files_lock); if (!list_empty(&tty->tty_files)) { struct inode *inode; @@ -2186,7 +2186,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, drop_tty = 1; } } - file_list_unlock(); + spin_unlock(&tty_files_lock); tty_kref_put(tty); } /* Reset controlling tty. */ -- cgit v0.10.2 From d996b62a8df1d935b01319bf8defb95b5709f7b8 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:36 +1000 Subject: tty: fix fu_list abuse tty: fix fu_list abuse tty code abuses fu_list, which causes a bug in remount,ro handling. If a tty device node is opened on a filesystem, then the last link to the inode removed, the filesystem will be allowed to be remounted readonly. This is because fs_may_remount_ro does not find the 0 link tty inode on the file sb list (because the tty code incorrectly removed it to use for its own purpose). This can result in a filesystem with errors after it is marked "clean". Taking idea from Christoph's initial patch, allocate a tty private struct at file->private_data and put our required list fields in there, linking file and tty. This makes tty nodes behave the same way as other device nodes and avoid meddling with the vfs, and avoids this bug. The error handling is not trivial in the tty code, so for this bugfix, I take the simple approach of using __GFP_NOFAIL and don't worry about memory errors. This is not a problem because our allocator doesn't fail small allocs as a rule anyway. So proper error handling is left as an exercise for tty hackers. [ Arguably filesystem's device inode would ideally be divorced from the driver's pseudo inode when it is opened, but in practice it's not clear whether that will ever be worth implementing. ] Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig Cc: Alan Cox Cc: Greg Kroah-Hartman Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/drivers/char/pty.c b/drivers/char/pty.c index 2c64faa..c350d01 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -675,12 +675,8 @@ static int ptmx_open(struct inode *inode, struct file *filp) } set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ - filp->private_data = tty; - file_sb_list_del(filp); /* __dentry_open has put it on the sb list */ - spin_lock(&tty_files_lock); - list_add(&filp->f_u.fu_list, &tty->tty_files); - spin_unlock(&tty_files_lock); + tty_add_file(tty, filp); retval = devpts_pty_new(inode, tty->link); if (retval) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index cd5b829..949067a 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -188,6 +188,41 @@ void free_tty_struct(struct tty_struct *tty) kfree(tty); } +static inline struct tty_struct *file_tty(struct file *file) +{ + return ((struct tty_file_private *)file->private_data)->tty; +} + +/* Associate a new file with the tty structure */ +void tty_add_file(struct tty_struct *tty, struct file *file) +{ + struct tty_file_private *priv; + + /* XXX: must implement proper error handling in callers */ + priv = kmalloc(sizeof(*priv), GFP_KERNEL|__GFP_NOFAIL); + + priv->tty = tty; + priv->file = file; + file->private_data = priv; + + spin_lock(&tty_files_lock); + list_add(&priv->list, &tty->tty_files); + spin_unlock(&tty_files_lock); +} + +/* Delete file from its tty */ +void tty_del_file(struct file *file) +{ + struct tty_file_private *priv = file->private_data; + + spin_lock(&tty_files_lock); + list_del(&priv->list); + spin_unlock(&tty_files_lock); + file->private_data = NULL; + kfree(priv); +} + + #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base) /** @@ -500,6 +535,7 @@ void __tty_hangup(struct tty_struct *tty) struct file *cons_filp = NULL; struct file *filp, *f = NULL; struct task_struct *p; + struct tty_file_private *priv; int closecount = 0, n; unsigned long flags; int refs = 0; @@ -509,7 +545,7 @@ void __tty_hangup(struct tty_struct *tty) spin_lock(&redirect_lock); - if (redirect && redirect->private_data == tty) { + if (redirect && file_tty(redirect) == tty) { f = redirect; redirect = NULL; } @@ -524,7 +560,8 @@ void __tty_hangup(struct tty_struct *tty) spin_lock(&tty_files_lock); /* This breaks for file handles being sent over AF_UNIX sockets ? */ - list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) { + list_for_each_entry(priv, &tty->tty_files, list) { + filp = priv->file; if (filp->f_op->write == redirected_tty_write) cons_filp = filp; if (filp->f_op->write != tty_write) @@ -892,12 +929,10 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { int i; - struct tty_struct *tty; - struct inode *inode; + struct inode *inode = file->f_path.dentry->d_inode; + struct tty_struct *tty = file_tty(file); struct tty_ldisc *ld; - tty = file->private_data; - inode = file->f_path.dentry->d_inode; if (tty_paranoia_check(tty, inode, "tty_read")) return -EIO; if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags))) @@ -1068,12 +1103,11 @@ void tty_write_message(struct tty_struct *tty, char *msg) static ssize_t tty_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { - struct tty_struct *tty; struct inode *inode = file->f_path.dentry->d_inode; + struct tty_struct *tty = file_tty(file); + struct tty_ldisc *ld; ssize_t ret; - struct tty_ldisc *ld; - tty = file->private_data; if (tty_paranoia_check(tty, inode, "tty_write")) return -EIO; if (!tty || !tty->ops->write || @@ -1510,13 +1544,13 @@ static void release_tty(struct tty_struct *tty, int idx) int tty_release(struct inode *inode, struct file *filp) { - struct tty_struct *tty, *o_tty; + struct tty_struct *tty = file_tty(filp); + struct tty_struct *o_tty; int pty_master, tty_closing, o_tty_closing, do_sleep; int devpts; int idx; char buf[64]; - tty = filp->private_data; if (tty_paranoia_check(tty, inode, "tty_release_dev")) return 0; @@ -1674,11 +1708,7 @@ int tty_release(struct inode *inode, struct file *filp) * - do_tty_hangup no longer sees this file descriptor as * something that needs to be handled for hangups. */ - spin_lock(&tty_files_lock); - BUG_ON(list_empty(&filp->f_u.fu_list)); - list_del_init(&filp->f_u.fu_list); - spin_unlock(&tty_files_lock); - filp->private_data = NULL; + tty_del_file(filp); /* * Perform some housekeeping before deciding whether to return. @@ -1845,12 +1875,8 @@ got_driver: return PTR_ERR(tty); } - filp->private_data = tty; - BUG_ON(list_empty(&filp->f_u.fu_list)); - file_sb_list_del(filp); /* __dentry_open has put it on the sb list */ - spin_lock(&tty_files_lock); - list_add(&filp->f_u.fu_list, &tty->tty_files); - spin_unlock(&tty_files_lock); + tty_add_file(tty, filp); + check_tty_count(tty, "tty_open"); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) @@ -1926,11 +1952,10 @@ got_driver: static unsigned int tty_poll(struct file *filp, poll_table *wait) { - struct tty_struct *tty; + struct tty_struct *tty = file_tty(filp); struct tty_ldisc *ld; int ret = 0; - tty = filp->private_data; if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll")) return 0; @@ -1943,11 +1968,10 @@ static unsigned int tty_poll(struct file *filp, poll_table *wait) static int __tty_fasync(int fd, struct file *filp, int on) { - struct tty_struct *tty; + struct tty_struct *tty = file_tty(filp); unsigned long flags; int retval = 0; - tty = filp->private_data; if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync")) goto out; @@ -2501,13 +2525,13 @@ EXPORT_SYMBOL(tty_pair_get_pty); */ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { - struct tty_struct *tty, *real_tty; + struct tty_struct *tty = file_tty(file); + struct tty_struct *real_tty; void __user *p = (void __user *)arg; int retval; struct tty_ldisc *ld; struct inode *inode = file->f_dentry->d_inode; - tty = file->private_data; if (tty_paranoia_check(tty, inode, "tty_ioctl")) return -EINVAL; @@ -2629,7 +2653,7 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct inode *inode = file->f_dentry->d_inode; - struct tty_struct *tty = file->private_data; + struct tty_struct *tty = file_tty(file); struct tty_ldisc *ld; int retval = -ENOIOCTLCMD; @@ -2721,7 +2745,7 @@ void __do_SAK(struct tty_struct *tty) if (!filp) continue; if (filp->f_op->read == tty_read && - filp->private_data == tty) { + file_tty(filp) == tty) { printk(KERN_NOTICE "SAK: killed process %d" " (%s): fd#%d opened to the tty\n", task_pid_nr(p), p->comm, i); diff --git a/fs/internal.h b/fs/internal.h index 6b706bc..6a5c13a8 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -80,6 +80,8 @@ extern void chroot_fs_refs(struct path *, struct path *); /* * file_table.c */ +extern void file_sb_list_add(struct file *f, struct super_block *sb); +extern void file_sb_list_del(struct file *f); extern void mark_files_ro(struct super_block *); extern struct file *get_empty_filp(void); diff --git a/include/linux/fs.h b/include/linux/fs.h index 5a9a9e5..5e65add 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2185,8 +2185,6 @@ static inline void insert_inode_hash(struct inode *inode) { __insert_inode_hash(inode, inode->i_ino); } -extern void file_sb_list_add(struct file *f, struct super_block *sb); -extern void file_sb_list_del(struct file *f); #ifdef CONFIG_BLOCK extern void submit_bio(int, struct bio *); extern int bdev_read_only(struct block_device *); diff --git a/include/linux/tty.h b/include/linux/tty.h index f6b371a..67d64e6 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -329,6 +329,13 @@ struct tty_struct { struct tty_port *port; }; +/* Each of a tty's open files has private_data pointing to tty_file_private */ +struct tty_file_private { + struct tty_struct *tty; + struct file *file; + struct list_head list; +}; + /* tty magic number */ #define TTY_MAGIC 0x5401 @@ -458,6 +465,7 @@ extern void proc_clear_tty(struct task_struct *p); extern struct tty_struct *get_current_tty(void); extern void tty_default_fops(struct file_operations *fops); extern struct tty_struct *alloc_tty_struct(void); +extern void tty_add_file(struct tty_struct *tty, struct file *file); extern void free_tty_struct(struct tty_struct *tty); extern void initialize_tty_struct(struct tty_struct *tty, struct tty_driver *driver, int idx); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index bd7da0f..4796ddd 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2172,6 +2172,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, if (tty) { spin_lock(&tty_files_lock); if (!list_empty(&tty->tty_files)) { + struct tty_file_private *file_priv; struct inode *inode; /* Revalidate access to controlling tty. @@ -2179,7 +2180,9 @@ static inline void flush_unauthorized_files(const struct cred *cred, than using file_has_perm, as this particular open file may belong to another process and we are only interested in the inode-based check here. */ - file = list_first_entry(&tty->tty_files, struct file, f_u.fu_list); + file_priv = list_first_entry(&tty->tty_files, + struct tty_file_private, list); + file = file_priv->file; inode = file->f_path.dentry->d_inode; if (inode_has_perm(cred, inode, FILE__READ | FILE__WRITE, NULL)) { -- cgit v0.10.2 From 2dc91abe03d8ce6dd7f9251faffafca5f6b9e85d Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:37 +1000 Subject: lglock: introduce special lglock and brlock spin locks lglock: introduce special lglock and brlock spin locks This patch introduces "local-global" locks (lglocks). These can be used to: - Provide fast exclusive access to per-CPU data, with exclusive access to another CPU's data allowed but possibly subject to contention, and to provide very slow exclusive access to all per-CPU data. - Or to provide very fast and scalable read serialisation, and to provide very slow exclusive serialisation of data (not necessarily per-CPU data). Brlocks are also implemented as a short-hand notation for the latter use case. Thanks to Paul for local/global naming convention. Cc: linux-kernel@vger.kernel.org Cc: Al Viro Cc: "Paul E. McKenney" Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/include/linux/lglock.h b/include/linux/lglock.h new file mode 100644 index 0000000..b288cb7 --- /dev/null +++ b/include/linux/lglock.h @@ -0,0 +1,172 @@ +/* + * Specialised local-global spinlock. Can only be declared as global variables + * to avoid overhead and keep things simple (and we don't want to start using + * these inside dynamically allocated structures). + * + * "local/global locks" (lglocks) can be used to: + * + * - Provide fast exclusive access to per-CPU data, with exclusive access to + * another CPU's data allowed but possibly subject to contention, and to + * provide very slow exclusive access to all per-CPU data. + * - Or to provide very fast and scalable read serialisation, and to provide + * very slow exclusive serialisation of data (not necessarily per-CPU data). + * + * Brlocks are also implemented as a short-hand notation for the latter use + * case. + * + * Copyright 2009, 2010, Nick Piggin, Novell Inc. + */ +#ifndef __LINUX_LGLOCK_H +#define __LINUX_LGLOCK_H + +#include +#include +#include + +/* can make br locks by using local lock for read side, global lock for write */ +#define br_lock_init(name) name##_lock_init() +#define br_read_lock(name) name##_local_lock() +#define br_read_unlock(name) name##_local_unlock() +#define br_write_lock(name) name##_global_lock_online() +#define br_write_unlock(name) name##_global_unlock_online() + +#define DECLARE_BRLOCK(name) DECLARE_LGLOCK(name) +#define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name) + + +#define lg_lock_init(name) name##_lock_init() +#define lg_local_lock(name) name##_local_lock() +#define lg_local_unlock(name) name##_local_unlock() +#define lg_local_lock_cpu(name, cpu) name##_local_lock_cpu(cpu) +#define lg_local_unlock_cpu(name, cpu) name##_local_unlock_cpu(cpu) +#define lg_global_lock(name) name##_global_lock() +#define lg_global_unlock(name) name##_global_unlock() +#define lg_global_lock_online(name) name##_global_lock_online() +#define lg_global_unlock_online(name) name##_global_unlock_online() + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +#define LOCKDEP_INIT_MAP lockdep_init_map + +#define DEFINE_LGLOCK_LOCKDEP(name) \ + struct lock_class_key name##_lock_key; \ + struct lockdep_map name##_lock_dep_map; \ + EXPORT_SYMBOL(name##_lock_dep_map) + +#else +#define LOCKDEP_INIT_MAP(a, b, c, d) + +#define DEFINE_LGLOCK_LOCKDEP(name) +#endif + + +#define DECLARE_LGLOCK(name) \ + extern void name##_lock_init(void); \ + extern void name##_local_lock(void); \ + extern void name##_local_unlock(void); \ + extern void name##_local_lock_cpu(int cpu); \ + extern void name##_local_unlock_cpu(int cpu); \ + extern void name##_global_lock(void); \ + extern void name##_global_unlock(void); \ + extern void name##_global_lock_online(void); \ + extern void name##_global_unlock_online(void); \ + +#define DEFINE_LGLOCK(name) \ + \ + DEFINE_PER_CPU(arch_spinlock_t, name##_lock); \ + DEFINE_LGLOCK_LOCKDEP(name); \ + \ + void name##_lock_init(void) { \ + int i; \ + LOCKDEP_INIT_MAP(&name##_lock_dep_map, #name, &name##_lock_key, 0); \ + for_each_possible_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + *lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; \ + } \ + } \ + EXPORT_SYMBOL(name##_lock_init); \ + \ + void name##_local_lock(void) { \ + arch_spinlock_t *lock; \ + preempt_disable(); \ + rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \ + lock = &__get_cpu_var(name##_lock); \ + arch_spin_lock(lock); \ + } \ + EXPORT_SYMBOL(name##_local_lock); \ + \ + void name##_local_unlock(void) { \ + arch_spinlock_t *lock; \ + rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \ + lock = &__get_cpu_var(name##_lock); \ + arch_spin_unlock(lock); \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_local_unlock); \ + \ + void name##_local_lock_cpu(int cpu) { \ + arch_spinlock_t *lock; \ + preempt_disable(); \ + rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \ + lock = &per_cpu(name##_lock, cpu); \ + arch_spin_lock(lock); \ + } \ + EXPORT_SYMBOL(name##_local_lock_cpu); \ + \ + void name##_local_unlock_cpu(int cpu) { \ + arch_spinlock_t *lock; \ + rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \ + lock = &per_cpu(name##_lock, cpu); \ + arch_spin_unlock(lock); \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_local_unlock_cpu); \ + \ + void name##_global_lock_online(void) { \ + int i; \ + preempt_disable(); \ + rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ + for_each_online_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_lock(lock); \ + } \ + } \ + EXPORT_SYMBOL(name##_global_lock_online); \ + \ + void name##_global_unlock_online(void) { \ + int i; \ + rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \ + for_each_online_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_unlock(lock); \ + } \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_global_unlock_online); \ + \ + void name##_global_lock(void) { \ + int i; \ + preempt_disable(); \ + rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ + for_each_online_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_lock(lock); \ + } \ + } \ + EXPORT_SYMBOL(name##_global_lock); \ + \ + void name##_global_unlock(void) { \ + int i; \ + rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \ + for_each_online_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_unlock(lock); \ + } \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_global_unlock); +#endif -- cgit v0.10.2 From 6416ccb7899960868f5016751fb81bf25213d24f Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:38 +1000 Subject: fs: scale files_lock fs: scale files_lock Improve scalability of files_lock by adding per-cpu, per-sb files lists, protected with an lglock. The lglock provides fast access to the per-cpu lists to add and remove files. It also provides a snapshot of all the per-cpu lists (although this is very slow). One difficulty with this approach is that a file can be removed from the list by another CPU. We must track which per-cpu list the file is on with a new variale in the file struct (packed into a hole on 64-bit archs). Scalability could suffer if files are frequently removed from different cpu's list. However loads with frequent removal of files imply short interval between adding and removing the files, and the scheduler attempts to avoid moving processes too far away. Also, even in the case of cross-CPU removal, the hardware has much more opportunity to parallelise cacheline transfers with N cachelines than with 1. A worst-case test of 1 CPU allocating files subsequently being freed by N CPUs degenerates to contending on a single lock, which is no worse than before. When more than one CPU are allocating files, even if they are always freed by different CPUs, there will be more parallelism than the single-lock case. Testing results: On a 2 socket, 8 core opteron, I measure the number of times the lock is taken to remove the file, the number of times it is removed by the same CPU that added it, and the number of times it is removed by the same node that added it. Booting: locks= 25049 cpu-hits= 23174 (92.5%) node-hits= 23945 (95.6%) kbuild -j16 locks=2281913 cpu-hits=2208126 (96.8%) node-hits=2252674 (98.7%) dbench 64 locks=4306582 cpu-hits=4287247 (99.6%) node-hits=4299527 (99.8%) So a file is removed from the same CPU it was added by over 90% of the time. It remains within the same node 95% of the time. Tim Chen ran some numbers for a 64 thread Nehalem system performing a compile. throughput 2.6.34-rc2 24.5 +patch 24.9 us sys idle IO wait (in %) 2.6.34-rc2 51.25 28.25 17.25 3.25 +patch 53.75 18.5 19 8.75 So significantly less CPU time spent in kernel code, higher idle time and slightly higher throughput. Single threaded performance difference was within the noise of microbenchmarks. That is not to say penalty does not exist, the code is larger and more memory accesses required so it will be slightly slower. Cc: linux-kernel@vger.kernel.org Cc: Tim Chen Cc: Andi Kleen Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/fs/file_table.c b/fs/file_table.c index 6f0e62e..a04bdd8 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -20,7 +20,9 @@ #include #include #include +#include #include +#include #include #include @@ -32,7 +34,8 @@ struct files_stat_struct files_stat = { .max_files = NR_FILE }; -static __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); +DECLARE_LGLOCK(files_lglock); +DEFINE_LGLOCK(files_lglock); /* SLAB cache for file structures */ static struct kmem_cache *filp_cachep __read_mostly; @@ -336,30 +339,98 @@ void put_filp(struct file *file) } } +static inline int file_list_cpu(struct file *file) +{ +#ifdef CONFIG_SMP + return file->f_sb_list_cpu; +#else + return smp_processor_id(); +#endif +} + +/* helper for file_sb_list_add to reduce ifdefs */ +static inline void __file_sb_list_add(struct file *file, struct super_block *sb) +{ + struct list_head *list; +#ifdef CONFIG_SMP + int cpu; + cpu = smp_processor_id(); + file->f_sb_list_cpu = cpu; + list = per_cpu_ptr(sb->s_files, cpu); +#else + list = &sb->s_files; +#endif + list_add(&file->f_u.fu_list, list); +} + +/** + * file_sb_list_add - add a file to the sb's file list + * @file: file to add + * @sb: sb to add it to + * + * Use this function to associate a file with the superblock of the inode it + * refers to. + */ void file_sb_list_add(struct file *file, struct super_block *sb) { - spin_lock(&files_lock); - BUG_ON(!list_empty(&file->f_u.fu_list)); - list_add(&file->f_u.fu_list, &sb->s_files); - spin_unlock(&files_lock); + lg_local_lock(files_lglock); + __file_sb_list_add(file, sb); + lg_local_unlock(files_lglock); } +/** + * file_sb_list_del - remove a file from the sb's file list + * @file: file to remove + * @sb: sb to remove it from + * + * Use this function to remove a file from its superblock. + */ void file_sb_list_del(struct file *file) { if (!list_empty(&file->f_u.fu_list)) { - spin_lock(&files_lock); + lg_local_lock_cpu(files_lglock, file_list_cpu(file)); list_del_init(&file->f_u.fu_list); - spin_unlock(&files_lock); + lg_local_unlock_cpu(files_lglock, file_list_cpu(file)); } } +#ifdef CONFIG_SMP + +/* + * These macros iterate all files on all CPUs for a given superblock. + * files_lglock must be held globally. + */ +#define do_file_list_for_each_entry(__sb, __file) \ +{ \ + int i; \ + for_each_possible_cpu(i) { \ + struct list_head *list; \ + list = per_cpu_ptr((__sb)->s_files, i); \ + list_for_each_entry((__file), list, f_u.fu_list) + +#define while_file_list_for_each_entry \ + } \ +} + +#else + +#define do_file_list_for_each_entry(__sb, __file) \ +{ \ + struct list_head *list; \ + list = &(sb)->s_files; \ + list_for_each_entry((__file), list, f_u.fu_list) + +#define while_file_list_for_each_entry \ +} + +#endif + int fs_may_remount_ro(struct super_block *sb) { struct file *file; - /* Check that no files are currently opened for writing. */ - spin_lock(&files_lock); - list_for_each_entry(file, &sb->s_files, f_u.fu_list) { + lg_global_lock(files_lglock); + do_file_list_for_each_entry(sb, file) { struct inode *inode = file->f_path.dentry->d_inode; /* File with pending delete? */ @@ -369,11 +440,11 @@ int fs_may_remount_ro(struct super_block *sb) /* Writeable file? */ if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) goto too_bad; - } - spin_unlock(&files_lock); + } while_file_list_for_each_entry; + lg_global_unlock(files_lglock); return 1; /* Tis' cool bro. */ too_bad: - spin_unlock(&files_lock); + lg_global_unlock(files_lglock); return 0; } @@ -389,8 +460,8 @@ void mark_files_ro(struct super_block *sb) struct file *f; retry: - spin_lock(&files_lock); - list_for_each_entry(f, &sb->s_files, f_u.fu_list) { + lg_global_lock(files_lglock); + do_file_list_for_each_entry(sb, f) { struct vfsmount *mnt; if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) continue; @@ -406,12 +477,12 @@ retry: file_release_write(f); mnt = mntget(f->f_path.mnt); /* This can sleep, so we can't hold the spinlock. */ - spin_unlock(&files_lock); + lg_global_unlock(files_lglock); mnt_drop_write(mnt); mntput(mnt); goto retry; - } - spin_unlock(&files_lock); + } while_file_list_for_each_entry; + lg_global_unlock(files_lglock); } void __init files_init(unsigned long mempages) @@ -431,5 +502,6 @@ void __init files_init(unsigned long mempages) if (files_stat.max_files < NR_FILE) files_stat.max_files = NR_FILE; files_defer_init(); + lg_lock_init(files_lglock); percpu_counter_init(&nr_files, 0); } diff --git a/fs/super.c b/fs/super.c index 9674ab2..8819e3a 100644 --- a/fs/super.c +++ b/fs/super.c @@ -54,7 +54,22 @@ static struct super_block *alloc_super(struct file_system_type *type) s = NULL; goto out; } +#ifdef CONFIG_SMP + s->s_files = alloc_percpu(struct list_head); + if (!s->s_files) { + security_sb_free(s); + kfree(s); + s = NULL; + goto out; + } else { + int i; + + for_each_possible_cpu(i) + INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i)); + } +#else INIT_LIST_HEAD(&s->s_files); +#endif INIT_LIST_HEAD(&s->s_instances); INIT_HLIST_HEAD(&s->s_anon); INIT_LIST_HEAD(&s->s_inodes); @@ -108,6 +123,9 @@ out: */ static inline void destroy_super(struct super_block *s) { +#ifdef CONFIG_SMP + free_percpu(s->s_files); +#endif security_sb_free(s); kfree(s->s_subtype); kfree(s->s_options); diff --git a/include/linux/fs.h b/include/linux/fs.h index 5e65add..76041b6 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -920,6 +920,9 @@ struct file { #define f_vfsmnt f_path.mnt const struct file_operations *f_op; spinlock_t f_lock; /* f_ep_links, f_flags, no IRQ */ +#ifdef CONFIG_SMP + int f_sb_list_cpu; +#endif atomic_long_t f_count; unsigned int f_flags; fmode_t f_mode; @@ -1334,7 +1337,11 @@ struct super_block { struct list_head s_inodes; /* all inodes */ struct hlist_head s_anon; /* anonymous dentries for (nfs) exporting */ +#ifdef CONFIG_SMP + struct list_head __percpu *s_files; +#else struct list_head s_files; +#endif /* s_dentry_lru and s_nr_dentry_unused are protected by dcache_lock */ struct list_head s_dentry_lru; /* unused dentry lru */ int s_nr_dentry_unused; /* # of dentry on lru */ -- cgit v0.10.2 From 99b7db7b8ffd6bb755eb0a175596421a0b581cb2 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:39 +1000 Subject: fs: brlock vfsmount_lock fs: brlock vfsmount_lock Use a brlock for the vfsmount lock. It must be taken for write whenever modifying the mount hash or associated fields, and may be taken for read when performing mount hash lookups. A new lock is added for the mnt-id allocator, so it doesn't need to take the heavy vfsmount write-lock. The number of atomics should remain the same for fastpath rlock cases, though code would be slightly slower due to per-cpu access. Scalability is not not be much improved in common cases yet, due to other locks (ie. dcache_lock) getting in the way. However path lookups crossing mountpoints should be one case where scalability is improved (currently requiring the global lock). The slowpath is slower due to use of brlock. On a 64 core, 64 socket, 32 node Altix system (high latency to remote nodes), a simple umount microbenchmark (mount --bind mnt mnt2 ; umount mnt2 loop 1000 times), before this patch it took 6.8s, afterwards took 7.1s, about 5% slower. Cc: Al Viro Signed-off-by: Nick Piggin Signed-off-by: Al Viro diff --git a/fs/dcache.c b/fs/dcache.c index d56a40b..83293be 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1935,7 +1935,7 @@ static int prepend_path(const struct path *path, struct path *root, bool slash = false; int error = 0; - spin_lock(&vfsmount_lock); + br_read_lock(vfsmount_lock); while (dentry != root->dentry || vfsmnt != root->mnt) { struct dentry * parent; @@ -1964,7 +1964,7 @@ out: if (!error && !slash) error = prepend(buffer, buflen, "/", 1); - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); return error; global_root: @@ -2302,11 +2302,12 @@ int path_is_under(struct path *path1, struct path *path2) struct vfsmount *mnt = path1->mnt; struct dentry *dentry = path1->dentry; int res; - spin_lock(&vfsmount_lock); + + br_read_lock(vfsmount_lock); if (mnt != path2->mnt) { for (;;) { if (mnt->mnt_parent == mnt) { - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); return 0; } if (mnt->mnt_parent == path2->mnt) @@ -2316,7 +2317,7 @@ int path_is_under(struct path *path1, struct path *path2) dentry = mnt->mnt_mountpoint; } res = is_subdir(dentry, path2->dentry); - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); return res; } EXPORT_SYMBOL(path_is_under); diff --git a/fs/internal.h b/fs/internal.h index 6a5c13a8..a6910e9 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -9,6 +9,8 @@ * 2 of the License, or (at your option) any later version. */ +#include + struct super_block; struct linux_binprm; struct path; @@ -70,7 +72,8 @@ extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int); extern void __init mnt_init(void); -extern spinlock_t vfsmount_lock; +DECLARE_BRLOCK(vfsmount_lock); + /* * fs_struct.c diff --git a/fs/namei.c b/fs/namei.c index 11de7c3..24896e8 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -595,15 +595,16 @@ int follow_up(struct path *path) { struct vfsmount *parent; struct dentry *mountpoint; - spin_lock(&vfsmount_lock); + + br_read_lock(vfsmount_lock); parent = path->mnt->mnt_parent; if (parent == path->mnt) { - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); return 0; } mntget(parent); mountpoint = dget(path->mnt->mnt_mountpoint); - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); dput(path->dentry); path->dentry = mountpoint; mntput(path->mnt); diff --git a/fs/namespace.c b/fs/namespace.c index 2e10cb1..de402eb 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -11,6 +11,8 @@ #include #include #include +#include +#include #include #include #include @@ -38,12 +40,10 @@ #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) #define HASH_SIZE (1UL << HASH_SHIFT) -/* spinlock for vfsmount related operations, inplace of dcache_lock */ -__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); - static int event; static DEFINE_IDA(mnt_id_ida); static DEFINE_IDA(mnt_group_ida); +static DEFINE_SPINLOCK(mnt_id_lock); static int mnt_id_start = 0; static int mnt_group_start = 1; @@ -55,6 +55,16 @@ static struct rw_semaphore namespace_sem; struct kobject *fs_kobj; EXPORT_SYMBOL_GPL(fs_kobj); +/* + * vfsmount lock may be taken for read to prevent changes to the + * vfsmount hash, ie. during mountpoint lookups or walking back + * up the tree. + * + * It should be taken for write in all cases where the vfsmount + * tree or hash is modified or when a vfsmount structure is modified. + */ +DEFINE_BRLOCK(vfsmount_lock); + static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) { unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); @@ -65,18 +75,21 @@ static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) -/* allocation is serialized by namespace_sem */ +/* + * allocation is serialized by namespace_sem, but we need the spinlock to + * serialize with freeing. + */ static int mnt_alloc_id(struct vfsmount *mnt) { int res; retry: ida_pre_get(&mnt_id_ida, GFP_KERNEL); - spin_lock(&vfsmount_lock); + spin_lock(&mnt_id_lock); res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); if (!res) mnt_id_start = mnt->mnt_id + 1; - spin_unlock(&vfsmount_lock); + spin_unlock(&mnt_id_lock); if (res == -EAGAIN) goto retry; @@ -86,11 +99,11 @@ retry: static void mnt_free_id(struct vfsmount *mnt) { int id = mnt->mnt_id; - spin_lock(&vfsmount_lock); + spin_lock(&mnt_id_lock); ida_remove(&mnt_id_ida, id); if (mnt_id_start > id) mnt_id_start = id; - spin_unlock(&vfsmount_lock); + spin_unlock(&mnt_id_lock); } /* @@ -348,7 +361,7 @@ static int mnt_make_readonly(struct vfsmount *mnt) { int ret = 0; - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); mnt->mnt_flags |= MNT_WRITE_HOLD; /* * After storing MNT_WRITE_HOLD, we'll read the counters. This store @@ -382,15 +395,15 @@ static int mnt_make_readonly(struct vfsmount *mnt) */ smp_wmb(); mnt->mnt_flags &= ~MNT_WRITE_HOLD; - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); return ret; } static void __mnt_unmake_readonly(struct vfsmount *mnt) { - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); mnt->mnt_flags &= ~MNT_READONLY; - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); } void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) @@ -414,6 +427,7 @@ void free_vfsmnt(struct vfsmount *mnt) /* * find the first or last mount at @dentry on vfsmount @mnt depending on * @dir. If @dir is set return the first mount else return the last mount. + * vfsmount_lock must be held for read or write. */ struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, int dir) @@ -443,10 +457,11 @@ struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, struct vfsmount *lookup_mnt(struct path *path) { struct vfsmount *child_mnt; - spin_lock(&vfsmount_lock); + + br_read_lock(vfsmount_lock); if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) mntget(child_mnt); - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); return child_mnt; } @@ -455,6 +470,9 @@ static inline int check_mnt(struct vfsmount *mnt) return mnt->mnt_ns == current->nsproxy->mnt_ns; } +/* + * vfsmount lock must be held for write + */ static void touch_mnt_namespace(struct mnt_namespace *ns) { if (ns) { @@ -463,6 +481,9 @@ static void touch_mnt_namespace(struct mnt_namespace *ns) } } +/* + * vfsmount lock must be held for write + */ static void __touch_mnt_namespace(struct mnt_namespace *ns) { if (ns && ns->event != event) { @@ -471,6 +492,9 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns) } } +/* + * vfsmount lock must be held for write + */ static void detach_mnt(struct vfsmount *mnt, struct path *old_path) { old_path->dentry = mnt->mnt_mountpoint; @@ -482,6 +506,9 @@ static void detach_mnt(struct vfsmount *mnt, struct path *old_path) old_path->dentry->d_mounted--; } +/* + * vfsmount lock must be held for write + */ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, struct vfsmount *child_mnt) { @@ -490,6 +517,9 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, dentry->d_mounted++; } +/* + * vfsmount lock must be held for write + */ static void attach_mnt(struct vfsmount *mnt, struct path *path) { mnt_set_mountpoint(path->mnt, path->dentry, mnt); @@ -499,7 +529,7 @@ static void attach_mnt(struct vfsmount *mnt, struct path *path) } /* - * the caller must hold vfsmount_lock + * vfsmount lock must be held for write */ static void commit_tree(struct vfsmount *mnt) { @@ -623,39 +653,43 @@ static inline void __mntput(struct vfsmount *mnt) void mntput_no_expire(struct vfsmount *mnt) { repeat: - if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { - if (likely(!mnt->mnt_pinned)) { - spin_unlock(&vfsmount_lock); - __mntput(mnt); - return; - } - atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); - mnt->mnt_pinned = 0; - spin_unlock(&vfsmount_lock); - acct_auto_close_mnt(mnt); - goto repeat; + if (atomic_add_unless(&mnt->mnt_count, -1, 1)) + return; + br_write_lock(vfsmount_lock); + if (!atomic_dec_and_test(&mnt->mnt_count)) { + br_write_unlock(vfsmount_lock); + return; + } + if (likely(!mnt->mnt_pinned)) { + br_write_unlock(vfsmount_lock); + __mntput(mnt); + return; } + atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); + mnt->mnt_pinned = 0; + br_write_unlock(vfsmount_lock); + acct_auto_close_mnt(mnt); + goto repeat; } - EXPORT_SYMBOL(mntput_no_expire); void mnt_pin(struct vfsmount *mnt) { - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); mnt->mnt_pinned++; - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); } EXPORT_SYMBOL(mnt_pin); void mnt_unpin(struct vfsmount *mnt) { - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); if (mnt->mnt_pinned) { atomic_inc(&mnt->mnt_count); mnt->mnt_pinned--; } - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); } EXPORT_SYMBOL(mnt_unpin); @@ -746,12 +780,12 @@ int mnt_had_events(struct proc_mounts *p) struct mnt_namespace *ns = p->ns; int res = 0; - spin_lock(&vfsmount_lock); + br_read_lock(vfsmount_lock); if (p->event != ns->event) { p->event = ns->event; res = 1; } - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); return res; } @@ -952,12 +986,12 @@ int may_umount_tree(struct vfsmount *mnt) int minimum_refs = 0; struct vfsmount *p; - spin_lock(&vfsmount_lock); + br_read_lock(vfsmount_lock); for (p = mnt; p; p = next_mnt(p, mnt)) { actual_refs += atomic_read(&p->mnt_count); minimum_refs += 2; } - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); if (actual_refs > minimum_refs) return 0; @@ -984,10 +1018,10 @@ int may_umount(struct vfsmount *mnt) { int ret = 1; down_read(&namespace_sem); - spin_lock(&vfsmount_lock); + br_read_lock(vfsmount_lock); if (propagate_mount_busy(mnt, 2)) ret = 0; - spin_unlock(&vfsmount_lock); + br_read_unlock(vfsmount_lock); up_read(&namespace_sem); return ret; } @@ -1003,13 +1037,14 @@ void release_mounts(struct list_head *head) if (mnt->mnt_parent != mnt) { struct dentry *dentry; struct vfsmount *m; - spin_lock(&vfsmount_lock); + + br_write_lock(vfsmount_lock); dentry = mnt->mnt_mountpoint; m = mnt->mnt_parent; mnt->mnt_mountpoint = mnt->mnt_root; mnt->mnt_parent = mnt; m->mnt_ghosts--; - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); dput(dentry); mntput(m); } @@ -1017,6 +1052,10 @@ void release_mounts(struct list_head *head) } } +/* + * vfsmount lock must be held for write + * namespace_sem must be held for write + */ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) { struct vfsmount *p; @@ -1107,7 +1146,7 @@ static int do_umount(struct vfsmount *mnt, int flags) } down_write(&namespace_sem); - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); event++; if (!(flags & MNT_DETACH)) @@ -1119,7 +1158,7 @@ static int do_umount(struct vfsmount *mnt, int flags) umount_tree(mnt, 1, &umount_list); retval = 0; } - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); up_write(&namespace_sem); release_mounts(&umount_list); return retval; @@ -1231,19 +1270,19 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, q = clone_mnt(p, p->mnt_root, flag); if (!q) goto Enomem; - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); list_add_tail(&q->mnt_list, &res->mnt_list); attach_mnt(q, &path); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); } } return res; Enomem: if (res) { LIST_HEAD(umount_list); - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); umount_tree(res, 0, &umount_list); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); release_mounts(&umount_list); } return NULL; @@ -1262,9 +1301,9 @@ void drop_collected_mounts(struct vfsmount *mnt) { LIST_HEAD(umount_list); down_write(&namespace_sem); - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); umount_tree(mnt, 0, &umount_list); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); up_write(&namespace_sem); release_mounts(&umount_list); } @@ -1392,7 +1431,7 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, if (err) goto out_cleanup_ids; - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); if (IS_MNT_SHARED(dest_mnt)) { for (p = source_mnt; p; p = next_mnt(p, source_mnt)) @@ -1411,7 +1450,8 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, list_del_init(&child->mnt_hash); commit_tree(child); } - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); + return 0; out_cleanup_ids: @@ -1466,10 +1506,10 @@ static int do_change_type(struct path *path, int flag) goto out_unlock; } - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) change_mnt_propagation(m, type); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); out_unlock: up_write(&namespace_sem); @@ -1513,9 +1553,10 @@ static int do_loopback(struct path *path, char *old_name, err = graft_tree(mnt, path); if (err) { LIST_HEAD(umount_list); - spin_lock(&vfsmount_lock); + + br_write_lock(vfsmount_lock); umount_tree(mnt, 0, &umount_list); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); release_mounts(&umount_list); } @@ -1568,16 +1609,16 @@ static int do_remount(struct path *path, int flags, int mnt_flags, else err = do_remount_sb(sb, flags, data, 0); if (!err) { - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK; path->mnt->mnt_flags = mnt_flags; - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); } up_write(&sb->s_umount); if (!err) { - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); touch_mnt_namespace(path->mnt->mnt_ns); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); } return err; } @@ -1754,7 +1795,7 @@ void mark_mounts_for_expiry(struct list_head *mounts) return; down_write(&namespace_sem); - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); /* extract from the expiration list every vfsmount that matches the * following criteria: @@ -1773,7 +1814,7 @@ void mark_mounts_for_expiry(struct list_head *mounts) touch_mnt_namespace(mnt->mnt_ns); umount_tree(mnt, 1, &umounts); } - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); up_write(&namespace_sem); release_mounts(&umounts); @@ -1830,6 +1871,8 @@ resume: /* * process a list of expirable mountpoints with the intent of discarding any * submounts of a specific parent mountpoint + * + * vfsmount_lock must be held for write */ static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) { @@ -2048,9 +2091,9 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, kfree(new_ns); return ERR_PTR(-ENOMEM); } - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); list_add_tail(&new_ns->list, &new_ns->root->mnt_list); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); /* * Second pass: switch the tsk->fs->* elements and mark new vfsmounts @@ -2244,7 +2287,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, goto out2; /* not attached */ /* make sure we can reach put_old from new_root */ tmp = old.mnt; - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); if (tmp != new.mnt) { for (;;) { if (tmp->mnt_parent == tmp) @@ -2264,7 +2307,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, /* mount new_root on / */ attach_mnt(new.mnt, &root_parent); touch_mnt_namespace(current->nsproxy->mnt_ns); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); chroot_fs_refs(&root, &new); error = 0; path_put(&root_parent); @@ -2279,7 +2322,7 @@ out1: out0: return error; out3: - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); goto out2; } @@ -2326,6 +2369,8 @@ void __init mnt_init(void) for (u = 0; u < HASH_SIZE; u++) INIT_LIST_HEAD(&mount_hashtable[u]); + br_lock_init(vfsmount_lock); + err = sysfs_init(); if (err) printk(KERN_WARNING "%s: sysfs_init error: %d\n", @@ -2344,9 +2389,9 @@ void put_mnt_ns(struct mnt_namespace *ns) if (!atomic_dec_and_test(&ns->count)) return; down_write(&namespace_sem); - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); umount_tree(ns->root, 0, &umount_list); - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); up_write(&namespace_sem); release_mounts(&umount_list); kfree(ns); diff --git a/fs/pnode.c b/fs/pnode.c index 5cc564a..8066b8d 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -126,6 +126,9 @@ static int do_make_slave(struct vfsmount *mnt) return 0; } +/* + * vfsmount lock must be held for write + */ void change_mnt_propagation(struct vfsmount *mnt, int type) { if (type == MS_SHARED) { @@ -270,12 +273,12 @@ int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry, prev_src_mnt = child; } out: - spin_lock(&vfsmount_lock); + br_write_lock(vfsmount_lock); while (!list_empty(&tmp_list)) { child = list_first_entry(&tmp_list, struct vfsmount, mnt_hash); umount_tree(child, 0, &umount_list); } - spin_unlock(&vfsmount_lock); + br_write_unlock(vfsmount_lock); release_mounts(&umount_list); return ret; } @@ -296,6 +299,8 @@ static inline int do_refcount_check(struct vfsmount *mnt, int count) * other mounts its parent propagates to. * Check if any of these mounts that **do not have submounts** * have more references than 'refcnt'. If so return busy. + * + * vfsmount lock must be held for read or write */ int propagate_mount_busy(struct vfsmount *mnt, int refcnt) { @@ -353,6 +358,8 @@ static void __propagate_umount(struct vfsmount *mnt) * collect all mounts that receive propagation from the mount in @list, * and return these additional mounts in the same list. * @list: the list of mounts to be unmounted. + * + * vfsmount lock must be held for write */ int propagate_umount(struct list_head *list) { -- cgit v0.10.2