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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
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')
-rw-r--r--include/linux/raid/bitmap.h15
-rw-r--r--include/linux/raid/md_k.h3
-rw-r--r--include/linux/raid/raid1.h13
3 files changed, 26 insertions, 5 deletions
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 4bf1659f8aa..9de99198caf 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -7,7 +7,7 @@
#define BITMAP_H 1
#define BITMAP_MAJOR 3
-#define BITMAP_MINOR 38
+#define BITMAP_MINOR 39
/*
* in-memory bitmap:
@@ -147,8 +147,9 @@ typedef struct bitmap_super_s {
__u32 state; /* 48 bitmap state information */
__u32 chunksize; /* 52 the bitmap chunk size in bytes */
__u32 daemon_sleep; /* 56 seconds between disk flushes */
+ __u32 write_behind; /* 60 number of outstanding write-behind writes */
- __u8 pad[256 - 60]; /* set to zero */
+ __u8 pad[256 - 64]; /* set to zero */
} bitmap_super_t;
/* notes:
@@ -226,6 +227,9 @@ struct bitmap {
unsigned long flags;
+ unsigned long max_write_behind; /* write-behind mode */
+ atomic_t behind_writes;
+
/*
* the bitmap daemon - periodically wakes up and sweeps the bitmap
* file, cleaning up bits and flushing out pages to disk as necessary
@@ -260,9 +264,10 @@ int bitmap_setallbits(struct bitmap *bitmap);
void bitmap_write_all(struct bitmap *bitmap);
/* these are exported */
-int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors);
-void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
- int success);
+int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
+ unsigned long sectors, int behind);
+void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
+ unsigned long sectors, int success, int behind);
int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int degraded);
void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted);
void bitmap_close_sync(struct bitmap *bitmap);
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
diff --git a/include/linux/raid/raid1.h b/include/linux/raid/raid1.h
index 9d93cf12e89..60e19b66754 100644
--- a/include/linux/raid/raid1.h
+++ b/include/linux/raid/raid1.h
@@ -80,6 +80,9 @@ struct r1bio_s {
atomic_t remaining; /* 'have we finished' count,
* used from IRQ handlers
*/
+ atomic_t behind_remaining; /* number of write-behind ios remaining
+ * in this BehindIO request
+ */
sector_t sector;
int sectors;
unsigned long state;
@@ -107,4 +110,14 @@ struct r1bio_s {
#define R1BIO_Uptodate 0
#define R1BIO_IsSync 1
#define R1BIO_Degraded 2
+#define R1BIO_BehindIO 3
+/* For write-behind requests, we call bi_end_io when
+ * the last non-write-behind device completes, providing
+ * any write was successful. Otherwise we call when
+ * any write-behind write succeeds, otherwise we call
+ * with failure when last write completes (and all failed).
+ * Record that bi_end_io was called with this flag...
+ */
+#define R1BIO_Returned 4
+
#endif