[PATCH] md: improve locking on 'safemode' and move superblock writes
When md marks the superblock dirty before a write, it calls
generic_make_request (to write the superblock) from within
generic_make_request (to write the first dirty block), which could cause
problems later.
With this patch, the superblock write is always done by the helper thread, and
write request are delayed until that write completes.
Also, the locking around marking the array dirty and writing the superblock is
improved to avoid possible races.
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>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 63b1c59..677ce49 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1411,6 +1411,9 @@
sector_t logical_sector, last_sector;
struct stripe_head *sh;
+ if (md_write_start(mddev, bi)==0)
+ return 0;
+
if (bio_data_dir(bi)==WRITE) {
disk_stat_inc(mddev->gendisk, writes);
disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi));
@@ -1423,8 +1426,7 @@
last_sector = bi->bi_sector + (bi->bi_size>>9);
bi->bi_next = NULL;
bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
- if ( bio_data_dir(bi) == WRITE )
- md_write_start(mddev);
+
for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
DEFINE_WAIT(w);