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authorNeilBrown <neilb@suse.de>2009-03-31 14:27:02 +1100
committerNeilBrown <neilb@suse.de>2009-03-31 14:27:02 +1100
commit1187cf0a3c8b647d08bc86e043563c8d2a327adc (patch)
tree759515a3fdcbf962f35255f90ea6c4d7c708391a /drivers/md/bitmap.c
parenteea1bf384e05b5ab747f8530c4fba9e9e6907fff (diff)
downloadlinux-stericsson-1187cf0a3c8b647d08bc86e043563c8d2a327adc.tar.gz
md: Allow write-intent bitmaps to have chunksize < PAGE_SIZE
md currently insists that the chunk size used for write-intent bitmaps (the amount of data that corresponds to one chunk) be at least one page. The reason for this restriction is lost in the mists of time, but a review of the code (and a vague memory) suggests that the only problem would be related to resync. Resync tries very hard to work in multiples of a page, but also needs to sync with units of a bitmap_chunk too. This connection comes out in the bitmap_start_sync call. So change bitmap_start_sync to always work in multiples of a page. If the bitmap chunk size is less that one page, we flag multiple chunks as 'syncing' and generally make them all appear to the resync routines like one chunk. All other code either already works with data ranges that could span multiple chunks, or explicitly only cares about a single chunk. Signed-off-by: Neil Brown <neilb@suse.de>
Diffstat (limited to 'drivers/md/bitmap.c')
-rw-r--r--drivers/md/bitmap.c36
1 files changed, 30 insertions, 6 deletions
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 719943763391..8fa3277f72dc 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -111,9 +111,10 @@ static int bitmap_checkpage(struct bitmap *bitmap, unsigned long page, int creat
unsigned char *mappage;
if (page >= bitmap->pages) {
- printk(KERN_ALERT
- "%s: invalid bitmap page request: %lu (> %lu)\n",
- bmname(bitmap), page, bitmap->pages-1);
+ /* This can happen if bitmap_start_sync goes beyond
+ * End-of-device while looking for a whole page.
+ * It is harmless.
+ */
return -EINVAL;
}
@@ -570,7 +571,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
reason = "unrecognized superblock version";
- else if (chunksize < PAGE_SIZE)
+ else if (chunksize < 512)
reason = "bitmap chunksize too small";
else if ((1 << ffz(~chunksize)) != chunksize)
reason = "bitmap chunksize not a power of 2";
@@ -1345,8 +1346,8 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
}
}
-int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
- int degraded)
+static int __bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
+ int degraded)
{
bitmap_counter_t *bmc;
int rv;
@@ -1374,6 +1375,29 @@ int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
return rv;
}
+int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
+ int degraded)
+{
+ /* bitmap_start_sync must always report on multiples of whole
+ * pages, otherwise resync (which is very PAGE_SIZE based) will
+ * get confused.
+ * So call __bitmap_start_sync repeatedly (if needed) until
+ * At least PAGE_SIZE>>9 blocks are covered.
+ * Return the 'or' of the result.
+ */
+ int rv = 0;
+ int blocks1;
+
+ *blocks = 0;
+ while (*blocks < (PAGE_SIZE>>9)) {
+ rv |= __bitmap_start_sync(bitmap, offset,
+ &blocks1, degraded);
+ offset += blocks1;
+ *blocks += blocks1;
+ }
+ return rv;
+}
+
void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted)
{
bitmap_counter_t *bmc;