diff options
| author | Daeho Jeong <daeho.jeong@samsung.com> | 2016-04-25 23:22:35 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2016-04-25 23:22:35 -0400 |
| commit | c8585c6fcaf2011de54c3592e80a634a2b9e1a7f (patch) | |
| tree | 66b440a3e710ab4b63ae20200735a594bffb74cd /fs/ext4/ext4.h | |
| parent | 4c54659269ecb799133758330e7ea2a6fa4c65ca (diff) | |
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/ext4.h')
| -rw-r--r-- | fs/ext4/ext4.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index cb00b1119ec9..ba5aecc07fbc 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -33,6 +33,7 @@ #include <linux/ratelimit.h> #include <crypto/hash.h> #include <linux/falloc.h> +#include <linux/percpu-rwsem.h> #ifdef __KERNEL__ #include <linux/compat.h> #endif @@ -1508,6 +1509,9 @@ struct ext4_sb_info { struct ratelimit_state s_err_ratelimit_state; struct ratelimit_state s_warning_ratelimit_state; struct ratelimit_state s_msg_ratelimit_state; + + /* Barrier between changing inodes' journal flags and writepages ops. */ + struct percpu_rw_semaphore s_journal_flag_rwsem; }; static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb) |