Due to the use of write-behind, it is possible for md to
write a page to the bitmap file that is still completing writeback.
This is not allowed.
With this patch, we detect those cases and either force a sync write,
or back off and try later, as appropriate.
Signed-off-by: Neil Brown <neilb@xxxxxxxxxxxxxxx>
### Diffstat output
./drivers/md/bitmap.c | 68 +++++++++++++++++++++++++++-----------------------
1 files changed, 38 insertions(+), 30 deletions(-)
diff ./drivers/md/bitmap.c~current~ ./drivers/md/bitmap.c
--- ./drivers/md/bitmap.c~current~ 2005-05-10 14:44:11.000000000 +1000
+++ ./drivers/md/bitmap.c 2005-05-10 14:55:51.000000000 +1000
@@ -313,7 +313,16 @@ static int write_page(struct bitmap *bit
if (bitmap->file == NULL)
return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
- lock_page(page);
+ if (wait)
+ lock_page(page);
+ else {
+ if (TestSetPageLocked(page))
+ return -EAGAIN; /* already locked */
+ if (PageWriteback(page)) {
+ unlock_page(page);
+ return -EAGAIN;
+ }
+ }
ret = page->mapping->a_ops->prepare_write(NULL, page, 0, PAGE_SIZE);
if (!ret)
@@ -400,7 +409,7 @@ int bitmap_update_sb(struct bitmap *bitm
if (!bitmap->mddev->degraded)
sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
kunmap(bitmap->sb_page);
- return write_page(bitmap, bitmap->sb_page, 0);
+ return write_page(bitmap, bitmap->sb_page, 1);
}
/* print out the bitmap file superblock */
@@ -762,6 +771,7 @@ int bitmap_unplug(struct bitmap *bitmap)
unsigned long i, attr, flags;
struct page *page;
int wait = 0;
+ int err;
if (!bitmap)
return 0;
@@ -782,9 +792,17 @@ int bitmap_unplug(struct bitmap *bitmap)
wait = 1;
spin_unlock_irqrestore(&bitmap->lock, flags);
- if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE))
- if (write_page(bitmap, page, 0))
+ if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE)) {
+ err = write_page(bitmap, page, 0);
+ if (err == -EAGAIN) {
+ if (attr & BITMAP_PAGE_DIRTY)
+ err = write_page(bitmap, page, 1);
+ else
+ err = 0;
+ }
+ if (err)
return 1;
+ }
}
if (wait) { /* if any writes were performed, we need to wait on them */
if (bitmap->file) {
@@ -1006,8 +1024,15 @@ int bitmap_daemon_work(struct bitmap *bi
}
spin_unlock_irqrestore(&bitmap->lock, flags);
if (attr & BITMAP_PAGE_NEEDWRITE) {
- if (write_page(bitmap, page, 0))
+ switch (write_page(bitmap, page, 0)) {
+ case -EAGAIN:
+ set_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
+ break;
+ case 0:
+ break;
+ default:
bitmap_file_kick(bitmap);
+ }
page_cache_release(page);
}
continue;
@@ -1020,6 +1045,10 @@ int bitmap_daemon_work(struct bitmap *bi
clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
spin_unlock_irqrestore(&bitmap->lock, flags);
err = write_page(bitmap, lastpage, 0);
+ if (err == -EAGAIN) {
+ err = 0;
+ set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+ }
} else {
set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1068,6 +1097,10 @@ int bitmap_daemon_work(struct bitmap *bi
clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
spin_unlock_irqrestore(&bitmap->lock, flags);
err = write_page(bitmap, lastpage, 0);
+ if (err == -EAGAIN) {
+ set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
+ err = 0;
+ }
} else {
set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1421,31 +1454,6 @@ static void bitmap_set_memory_bits(struc
}
}
-/* dirty the entire bitmap */
-int bitmap_setallbits(struct bitmap *bitmap)
-{
- unsigned long flags;
- unsigned long j;
-
- /* dirty the in-memory bitmap */
- bitmap_set_memory_bits(bitmap, 0, bitmap->chunks << CHUNK_BLOCK_SHIFT(bitmap), 1);
-
- /* dirty the bitmap file */
- for (j = 0; j < bitmap->file_pages; j++) {
- struct page *page = bitmap->filemap[j];
-
- spin_lock_irqsave(&bitmap->lock, flags);
- page_cache_get(page);
- spin_unlock_irqrestore(&bitmap->lock, flags);
- memset(kmap(page), 0xff, PAGE_SIZE);
- kunmap(page);
- if (write_page(bitmap, page, 0))
- return 1;
- }
-
- return 0;
-}
-
/*
* free memory that was allocated
*/
-
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