4.20-stable review patch. If anyone has any objections, please let me know.
------------------ From: Theodore Ts'o <ty...@mit.edu> commit 8fdd60f2ae3682caf2a7258626abc21eb4711892 upstream. This reverts commit ad211f3e94b314a910d4af03178a0b52a7d1ee0a. As Jan Kara pointed out, this change was unsafe since it means we lose the call to sync_mapping_buffers() in the nojournal case. The original point of the commit was avoid taking the inode mutex (since it causes a lockdep warning in generic/113); but we need the mutex in order to call sync_mapping_buffers(). The real fix to this problem was discussed here: https://lore.kernel.org/lkml/20181025150540.259281-4-bvanass...@acm.org The proposed patch was to fix a syzbot complaint, but the problem can also demonstrated via "kvm-xfstests -c nojournal generic/113". Multiple solutions were discused in the e-mail thread, but none have landed in the kernel as of this writing. Anyway, commit ad211f3e94b314 is absolutely the wrong way to suppress the lockdep, so revert it. Fixes: ad211f3e94b314a910d4af03178a0b52a7d1ee0a ("ext4: use ext4_write_inode() when fsyncing w/o a journal") Signed-off-by: Theodore Ts'o <ty...@mit.edu> Reported: Jan Kara <j...@suse.cz> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/ext4/fsync.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) --- a/fs/ext4/fsync.c +++ b/fs/ext4/fsync.c @@ -116,16 +116,8 @@ int ext4_sync_file(struct file *file, lo goto out; } - ret = file_write_and_wait_range(file, start, end); - if (ret) - return ret; - if (!journal) { - struct writeback_control wbc = { - .sync_mode = WB_SYNC_ALL - }; - - ret = ext4_write_inode(inode, &wbc); + ret = __generic_file_fsync(file, start, end, datasync); if (!ret) ret = ext4_sync_parent(inode); if (test_opt(inode->i_sb, BARRIER)) @@ -133,6 +125,9 @@ int ext4_sync_file(struct file *file, lo goto out; } + ret = file_write_and_wait_range(file, start, end); + if (ret) + return ret; /* * data=writeback,ordered: * The caller's filemap_fdatawrite()/wait will sync the data.
