The patch titled
Subject: mm: make snapshotting pages for stable writes a per-bio operation
has been added to the -mm tree. Its filename is
mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation.patch
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From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Subject: 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.
Finally, the MS_SNAP_STABLE mount flag (only used by ext3) is now
superfluous, so get rid of it.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Artem Bityutskiy <dedekind1@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/buffer.c | 9 ++++++++-
fs/ext3/super.c | 1 -
fs/jbd/commit.c | 4 ++--
include/linux/blk_types.h | 3 ++-
include/linux/buffer_head.h | 1 +
include/uapi/linux/fs.h | 1 -
mm/bounce.c | 21 +--------------------
mm/page-writeback.c | 4 ----
8 files changed, 14 insertions(+), 30 deletions(-)
diff -puN fs/buffer.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation fs/buffer.c
--- a/fs/buffer.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/fs/buffer.c
@@ -2949,7 +2949,7 @@ static void guard_bh_eod(int rw, struct
}
}
-int submit_bh(int rw, struct buffer_head * bh)
+int _submit_bh(int rw, struct buffer_head * bh, unsigned long flags)
{
struct bio *bio;
int ret = 0;
@@ -2984,6 +2984,7 @@ int submit_bh(int rw, struct buffer_head
bio->bi_end_io = end_bio_bh_io_sync;
bio->bi_private = bh;
+ bio->bi_flags |= flags;
/* Take care of bh's that straddle the end of the device */
guard_bh_eod(rw, bio, bh);
@@ -2997,6 +2998,12 @@ int submit_bh(int rw, struct buffer_head
bio_put(bio);
return ret;
}
+EXPORT_SYMBOL_GPL(_submit_bh);
+
+int submit_bh(int rw, struct buffer_head * bh)
+{
+ return _submit_bh(rw, bh, 0);
+}
EXPORT_SYMBOL(submit_bh);
/**
diff -puN fs/ext3/super.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation fs/ext3/super.c
--- a/fs/ext3/super.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/fs/ext3/super.c
@@ -2067,7 +2067,6 @@ static int ext3_fill_super (struct super
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;
diff -puN fs/jbd/commit.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation fs/jbd/commit.c
--- a/fs/jbd/commit.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/fs/jbd/commit.c
@@ -163,7 +163,7 @@ static void journal_do_submit_data(struc
for (i = 0; i < bufs; i++) {
wbuf[i]->b_end_io = end_buffer_write_sync;
/* We use-up our safety reference in submit_bh() */
- submit_bh(write_op, wbuf[i]);
+ _submit_bh(write_op, wbuf[i], 1 << BIO_SNAP_STABLE);
}
}
@@ -667,7 +667,7 @@ start_journal_io:
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
bh->b_end_io = journal_end_buffer_io_sync;
- submit_bh(write_op, bh);
+ _submit_bh(write_op, bh, 1 << BIO_SNAP_STABLE);
}
cond_resched();
diff -puN include/linux/blk_types.h~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation include/linux/blk_types.h
--- a/include/linux/blk_types.h~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/include/linux/blk_types.h
@@ -111,12 +111,13 @@ struct bio {
#define BIO_FS_INTEGRITY 9 /* fs owns integrity data, not block layer */
#define BIO_QUIET 10 /* Make BIO Quiet */
#define BIO_MAPPED_INTEGRITY 11/* integrity metadata has been remapped */
+#define BIO_SNAP_STABLE 12 /* bio data must be snapshotted during write */
/*
* Flags starting here get preserved by bio_reset() - this includes
* BIO_POOL_IDX()
*/
-#define BIO_RESET_BITS 12
+#define BIO_RESET_BITS 13
#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
diff -puN include/linux/buffer_head.h~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation include/linux/buffer_head.h
--- a/include/linux/buffer_head.h~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/include/linux/buffer_head.h
@@ -181,6 +181,7 @@ void ll_rw_block(int, int, struct buffer
int sync_dirty_buffer(struct buffer_head *bh);
int __sync_dirty_buffer(struct buffer_head *bh, int rw);
void write_dirty_buffer(struct buffer_head *bh, int rw);
+int _submit_bh(int, struct buffer_head *, unsigned long);
int submit_bh(int, struct buffer_head *);
void write_boundary_block(struct block_device *bdev,
sector_t bblock, unsigned blocksize);
diff -puN include/uapi/linux/fs.h~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation include/uapi/linux/fs.h
--- a/include/uapi/linux/fs.h~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/include/uapi/linux/fs.h
@@ -88,7 +88,6 @@ struct inodes_stat_t {
#define MS_STRICTATIME (1<<24) /* Always perform atime updates */
/* These sb flags are internal to the kernel */
-#define MS_SNAP_STABLE (1<<27) /* Snapshot pages during writeback, if needed */
#define MS_NOSEC (1<<28)
#define MS_BORN (1<<29)
#define MS_ACTIVE (1<<30)
diff -puN mm/bounce.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation mm/bounce.c
--- a/mm/bounce.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/mm/bounce.c
@@ -181,32 +181,13 @@ static void bounce_end_io_read_isa(struc
#ifdef CONFIG_NEED_BOUNCE_POOL
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);
}
#else
static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
diff -puN mm/page-writeback.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation mm/page-writeback.c
--- a/mm/page-writeback.c~mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation
+++ a/mm/page-writeback.c
@@ -2311,10 +2311,6 @@ void wait_for_stable_page(struct page *p
if (!bdi_cap_stable_pages_required(bdi))
return;
-#ifdef CONFIG_NEED_BOUNCE_POOL
- if (mapping->host->i_sb->s_flags & MS_SNAP_STABLE)
- return;
-#endif /* CONFIG_NEED_BOUNCE_POOL */
wait_on_page_writeback(page);
}
_
Patches currently in -mm which might be from darrick.wong@xxxxxxxxxx are
linux-next.patch
mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation.patch
mm-make-snapshotting-pages-for-stable-writes-a-per-bio-operation-fix.patch
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