path: root/mm/bounce.c
diff options
authorDarrick J. Wong <>2013-04-29 15:07:25 -0700
committerLinus Torvalds <>2013-04-29 15:54:33 -0700
commit7136851117744f1d291bed6d307432699d405109 (patch)
tree6dc7d6bef45e24ad0d3d5d1b9290a81109758172 /mm/bounce.c
parent106c992a5ebef28193cf5958e49ceff5e4aebb04 (diff)
mm: make snapshotting pages for stable writes a per-bio operation
Walking a bio's page mappings has proved problematic, so create a new bio flag to indicate that a bio's data needs to be snapshotted in order to guarantee stable pages during writeback. Next, for the one user (ext3/jbd) of snapshotting, hook all the places where writes can be initiated without PG_writeback set, and set BIO_SNAP_STABLE there. We must also flag journal "metadata" bios for stable writeout, since file data can be written through the journal. Finally, the MS_SNAP_STABLE mount flag (only used by ext3) is now superfluous, so get rid of it. [ rename _submit_bh()'s `flags' to `bio_flags', delobotomize the _submit_bh declaration] [ teeny cleanup] Signed-off-by: Darrick J. Wong <> Cc: Andy Lutomirski <> Cc: Adrian Hunter <> Cc: Artem Bityutskiy <> Reviewed-by: Jan Kara <> Cc: Jens Axboe <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/bounce.c')
1 files changed, 1 insertions, 20 deletions
diff --git a/mm/bounce.c b/mm/bounce.c
index 5f8901768602..a5c2ec3589cb 100644
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -181,32 +181,13 @@ static void bounce_end_io_read_isa(struct bio *bio, int err)
static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
- struct page *page;
- struct backing_dev_info *bdi;
- struct address_space *mapping;
- struct bio_vec *from;
- int i;
if (bio_data_dir(bio) != WRITE)
return 0;
if (!bdi_cap_stable_pages_required(&q->backing_dev_info))
return 0;
- /*
- * Based on the first page that has a valid mapping, decide whether or
- * not we have to employ bounce buffering to guarantee stable pages.
- */
- bio_for_each_segment(from, bio, i) {
- page = from->bv_page;
- mapping = page_mapping(page);
- if (!mapping)
- continue;
- bdi = mapping->backing_dev_info;
- return mapping->host->i_sb->s_flags & MS_SNAP_STABLE;
- }
- return 0;
+ return test_bit(BIO_SNAP_STABLE, &bio->bi_flags);
static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)