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| author | Daeho Jeong <daeho.jeong@samsung.com> | 2016-04-26 03:22:35 (GMT) |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2016-04-26 03:22:35 (GMT) |
| commit | c8585c6fcaf2011de54c3592e80a634a2b9e1a7f (patch) | |
| tree | 66b440a3e710ab4b63ae20200735a594bffb74cd /fs/ext4/super.c | |
| parent | 4c54659269ecb799133758330e7ea2a6fa4c65ca (diff) | |
| download | linux-c8585c6fcaf2011de54c3592e80a634a2b9e1a7f.tar.xz | |
ext4: fix races between changing inode journal mode and ext4_writepages
In ext4, there is a race condition between changing inode journal mode
and ext4_writepages(). While ext4_writepages() is executed on a
non-journalled mode inode, the inode's journal mode could be enabled
by ioctl() and then, some pages dirtied after switching the journal
mode will be still exposed to ext4_writepages() in non-journaled mode.
To resolve this problem, we use fs-wide per-cpu rw semaphore by Jan
Kara's suggestion because we don't want to waste ext4_inode_info's
space for this extra rare case.
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/ext4/super.c')
| -rw-r--r-- | fs/ext4/super.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 304c712..20c5d52 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -859,6 +859,7 @@ static void ext4_put_super(struct super_block *sb) percpu_counter_destroy(&sbi->s_freeinodes_counter); percpu_counter_destroy(&sbi->s_dirs_counter); percpu_counter_destroy(&sbi->s_dirtyclusters_counter); + percpu_free_rwsem(&sbi->s_journal_flag_rwsem); brelse(sbi->s_sbh); #ifdef CONFIG_QUOTA for (i = 0; i < EXT4_MAXQUOTAS; i++) @@ -3930,6 +3931,9 @@ no_journal: if (!err) err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0, GFP_KERNEL); + if (!err) + err = percpu_init_rwsem(&sbi->s_journal_flag_rwsem); + if (err) { ext4_msg(sb, KERN_ERR, "insufficient memory"); goto failed_mount6; |