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author | Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> | 2009-04-28 12:04:59 (GMT) |
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committer | Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> | 2009-05-09 04:36:57 (GMT) |
commit | 201913ed746c7724a40d33ee5a0b6a1fd2ef3193 (patch) | |
tree | 149cd7552a854055a2ed278234649a77914aaf96 /fs/nilfs2/mdt.c | |
parent | 85c2a74fabadfc561b75fbd7decc6bcbfe873d57 (diff) | |
download | linux-fsl-qoriq-201913ed746c7724a40d33ee5a0b6a1fd2ef3193.tar.xz |
nilfs2: fix circular locking dependency of writer mutex
This fixes the following circular locking dependency problem:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.30-rc3 #5
-------------------------------------------------------
segctord/3895 is trying to acquire lock:
(&nilfs->ns_writer_mutex){+.+...}, at: [<d0d02172>]
nilfs_mdt_get_block+0x89/0x20f [nilfs2]
but task is already holding lock:
(&bmap->b_sem){++++..}, at: [<d0d02d99>]
nilfs_bmap_propagate+0x14/0x2e [nilfs2]
which lock already depends on the new lock.
The bugfix is done by replacing call sites of nilfs_get_writer() which
are never called from read-only context with direct dereferencing of
pointer to a writable FS-instance.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Diffstat (limited to 'fs/nilfs2/mdt.c')
-rw-r--r-- | fs/nilfs2/mdt.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c index 47dd815..e1c6777 100644 --- a/fs/nilfs2/mdt.c +++ b/fs/nilfs2/mdt.c @@ -77,19 +77,22 @@ static int nilfs_mdt_create_block(struct inode *inode, unsigned long block, void *)) { struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs; - struct nilfs_sb_info *writer = NULL; struct super_block *sb = inode->i_sb; struct nilfs_transaction_info ti; struct buffer_head *bh; int err; if (!sb) { - writer = nilfs_get_writer(nilfs); - if (!writer) { + /* + * Make sure this function is not called from any + * read-only context. + */ + if (!nilfs->ns_writer) { + WARN_ON(1); err = -EROFS; goto out; } - sb = writer->s_super; + sb = nilfs->ns_writer->s_super; } nilfs_transaction_begin(sb, &ti, 0); @@ -127,8 +130,6 @@ static int nilfs_mdt_create_block(struct inode *inode, unsigned long block, err = nilfs_transaction_commit(sb); else nilfs_transaction_abort(sb); - if (writer) - nilfs_put_writer(nilfs); out: return err; } |