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| 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/inode.c | |
| parent | 4c54659269ecb799133758330e7ea2a6fa4c65ca (diff) | |
| download | linux-c8585c6fcaf2011de54c3592e80a634a2b9e1a7f.tar.bz2 | |
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/inode.c')
| -rw-r--r-- | fs/ext4/inode.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 779ef4c11bc1..4d8ebbe00456 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2612,11 +2612,14 @@ static int ext4_writepages(struct address_space *mapping, struct blk_plug plug; bool give_up_on_write = false; + percpu_down_read(&sbi->s_journal_flag_rwsem); trace_ext4_writepages(inode, wbc); - if (dax_mapping(mapping)) - return dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, - wbc); + if (dax_mapping(mapping)) { + ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, + wbc); + goto out_writepages; + } /* * No pages to write? This is mainly a kludge to avoid starting @@ -2786,6 +2789,7 @@ retry: out_writepages: trace_ext4_writepages_result(inode, wbc, ret, nr_to_write - wbc->nr_to_write); + percpu_up_read(&sbi->s_journal_flag_rwsem); return ret; } @@ -5436,6 +5440,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) journal_t *journal; handle_t *handle; int err; + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); /* * We have to be very careful here: changing a data block's @@ -5475,6 +5480,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) } } + percpu_down_write(&sbi->s_journal_flag_rwsem); jbd2_journal_lock_updates(journal); /* @@ -5491,6 +5497,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) err = jbd2_journal_flush(journal); if (err < 0) { jbd2_journal_unlock_updates(journal); + percpu_up_write(&sbi->s_journal_flag_rwsem); ext4_inode_resume_unlocked_dio(inode); return err; } @@ -5499,6 +5506,8 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) ext4_set_aops(inode); jbd2_journal_unlock_updates(journal); + percpu_up_write(&sbi->s_journal_flag_rwsem); + if (val) up_write(&EXT4_I(inode)->i_mmap_sem); ext4_inode_resume_unlocked_dio(inode); |