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authorDarrick J. Wong <darrick.wong@oracle.com>2013-02-21 16:42:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-21 17:22:20 -0800
commitffecfd1a72fccfcee3dabb99b9ecba9735318f90 (patch)
treea5c3caf67249ec811a2c2c95678d9349fd8e2412 /fs/ext3
parent13575ca14fcdacd1ad914d00bc63eb4d96280986 (diff)
downloadlinux-ffecfd1a72fccfcee3dabb99b9ecba9735318f90.tar.gz
block: optionally snapshot page contents to provide stable pages during write
This provides a band-aid to provide stable page writes on jbd without needing to backport the fixed locking and page writeback bit handling schemes of jbd2. The band-aid works by using bounce buffers to snapshot page contents instead of waiting. For those wondering about the ext3 bandage -- fixing the jbd locking (which was done as part of ext4dev years ago) is a lot of surgery, and setting PG_writeback on data pages when we actually hold the page lock dropped ext3 performance by nearly an order of magnitude. If we're going to migrate iscsi and raid to use stable page writes, the complaints about high latency will likely return. We might as well centralize their page snapshotting thing to one place. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Artem Bityutskiy <dedekind1@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Ron Minnich <rminnich@sandia.gov> Cc: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ext3')
-rw-r--r--fs/ext3/super.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 6e50223b329..4ba2683c1d4 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2065,6 +2065,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_JOURNAL_DATA ? "journal":
test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_ORDERED_DATA ? "ordered":
"writeback");
+ sb->s_flags |= MS_SNAP_STABLE;
return 0;