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authorNeilBrown <neilb@cse.unsw.edu.au>2005-09-09 16:23:47 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-09 16:39:10 -0700
commit4b6d287f627b5fb6a49f78f9e81649ff98c62bb7 (patch)
tree7b6cbc6a997e25a7fb6185da7129e539c4ffda8b /include/linux/raid/md_k.h
parent8ddf9efe6708f3674f0ddfeb6425fd27bea109a2 (diff)
[PATCH] md: add write-behind support for md/raid1
If a device is flagged 'WriteMostly' and the array has a bitmap, and the bitmap superblock indicates that write_behind is allowed, then write_behind is enabled for WriteMostly devices. Write requests will be acknowledges as complete to the caller (via b_end_io) when all non-WriteMostly devices have completed the write, but will not be cleared from the bitmap until all devices complete. This requires memory allocation to make a local copy of the data being written. If there is insufficient memory, then we fall-back on normal write semantics. Signed-Off-By: Paul Clements <paul.clements@steeleye.com> Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/raid/md_k.h')
-rw-r--r--include/linux/raid/md_k.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 7ef78e15ce0..2514e5fcda7 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -275,6 +275,9 @@ struct mddev_s
atomic_t writes_pending;
request_queue_t *queue; /* for plugging ... */
+ atomic_t write_behind; /* outstanding async IO */
+ unsigned int max_write_behind; /* 0 = sync */
+
struct bitmap *bitmap; /* the bitmap for the device */
struct file *bitmap_file; /* the bitmap file */
long bitmap_offset; /* offset from superblock of