| Message ID | 20170502150351.29452-2-jack@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 02, 2017 at 05:03:45PM +0200, Jan Kara wrote: > Commit b685d3d65ac7 "block: treat REQ_FUA and REQ_PREFLUSH as > synchronous" removed REQ_SYNC flag from WRITE_FUA implementation. > generic_make_request_checks() however strips REQ_FUA flag from a bio > when the storage doesn't report volatile write cache and thus write > effectively becomes asynchronous which can lead to performance > regressions. This affects superblock writes for ext4. Fix the problem > by marking superblock writes always as synchronous. > > Fixes: b685d3d65ac791406e0dfd8779cc9b3707fea5a3 > CC: linux-ext4@vger.kernel.org > CC: "Theodore Ts'o" <tytso@mit.edu> > Signed-off-by: Jan Kara <jack@suse.cz> Thanks, applied. - Ted
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index a9448db1cf7e..f902852ac13e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4629,7 +4629,7 @@ static int ext4_commit_super(struct super_block *sb, int sync) if (sync) { unlock_buffer(sbh); error = __sync_dirty_buffer(sbh, - test_opt(sb, BARRIER) ? REQ_FUA : REQ_SYNC); + REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0)); if (error) return error;
Commit b685d3d65ac7 "block: treat REQ_FUA and REQ_PREFLUSH as synchronous" removed REQ_SYNC flag from WRITE_FUA implementation. generic_make_request_checks() however strips REQ_FUA flag from a bio when the storage doesn't report volatile write cache and thus write effectively becomes asynchronous which can lead to performance regressions. This affects superblock writes for ext4. Fix the problem by marking superblock writes always as synchronous. Fixes: b685d3d65ac791406e0dfd8779cc9b3707fea5a3 CC: linux-ext4@vger.kernel.org CC: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)