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btrfs: hooks for readahead 

This adds the hooks needed for readahead. In the readpage_end_io_hook,
the extent state is checked for the EXTENT_READAHEAD flag. Only in this
case the readahead hook is called, to keep the impact on non-ra as low
as possible.
Additionally, a hook for a failed IO is added, otherwise readahead would
wait indefinitely for the extent to finish.

Changes for v2:
 - eliminate race condition

Signed-off-by: Arne Jansen <sensille@gmx.net>
This commit is contained in:
Arne Jansen 2011-06-10 13:55:54 +02:00
parent 7414a03fbf
commit 4bb31e928d
2 changed files with 38 additions and 1 deletions
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37
fs/btrfs/disk-io.c
View File

@ -609,11 +609,47 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
end = eb->start + end - 1;
err:
if (test_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) {
clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags);
btree_readahead_hook(root, eb, eb->start, ret);
}
free_extent_buffer(eb);
out:
return ret;
}
static int btree_io_failed_hook(struct bio *failed_bio,
struct page *page, u64 start, u64 end,
struct extent_state *state)
{
struct extent_io_tree *tree;
unsigned long len;
struct extent_buffer *eb;
struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
tree = &BTRFS_I(page->mapping->host)->io_tree;
if (page->private == EXTENT_PAGE_PRIVATE)
goto out;
if (!page->private)
goto out;
len = page->private >> 2;
WARN_ON(len == 0);
eb = alloc_extent_buffer(tree, start, len, page);
if (eb == NULL)
goto out;
if (test_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) {
clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags);
btree_readahead_hook(root, eb, eb->start, -EIO);
}
out:
return -EIO; /* we fixed nothing */
}
static void end_workqueue_bio(struct bio *bio, int err)
{
struct end_io_wq *end_io_wq = bio->bi_private;
@ -3166,6 +3202,7 @@ static int btrfs_cleanup_transaction(struct btrfs_root *root)
static struct extent_io_ops btree_extent_io_ops = {
.write_cache_pages_lock_hook = btree_lock_page_hook,
.readpage_end_io_hook = btree_readpage_end_io_hook,
.readpage_io_failed_hook = btree_io_failed_hook,
.submit_bio_hook = btree_submit_bio_hook,
/* note we're sharing with inode.c for the merge bio hook */
.merge_bio_hook = btrfs_merge_bio_hook,

2
fs/btrfs/extent_io.c
View File

@ -1731,7 +1731,7 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
if (!uptodate && tree->ops &&
tree->ops->readpage_io_failed_hook) {
ret = tree->ops->readpage_io_failed_hook(bio, page,
start, end, NULL);
start, end, state);
if (ret == 0) {
uptodate =
test_bit(BIO_UPTODATE, &bio->bi_flags);