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-rw-r--r--fs/btrfs/extent_io.c387
-rw-r--r--fs/btrfs/extent_io.h10
-rw-r--r--fs/btrfs/inode.c155
3 files changed, 393 insertions, 159 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index afebb95e349..624ef10d36c 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -17,6 +17,7 @@
#include "compat.h"
#include "ctree.h"
#include "btrfs_inode.h"
+#include "volumes.h"
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
@@ -1599,6 +1600,368 @@ static int check_page_writeback(struct extent_io_tree *tree,
return 0;
}
+/*
+ * When IO fails, either with EIO or csum verification fails, we
+ * try other mirrors that might have a good copy of the data. This
+ * io_failure_record is used to record state as we go through all the
+ * mirrors. If another mirror has good data, the page is set up to date
+ * and things continue. If a good mirror can't be found, the original
+ * bio end_io callback is called to indicate things have failed.
+ */
+struct io_failure_record {
+ struct page *page;
+ u64 start;
+ u64 len;
+ u64 logical;
+ unsigned long bio_flags;
+ int this_mirror;
+ int failed_mirror;
+ int in_validation;
+};
+
+static int free_io_failure(struct inode *inode, struct io_failure_record *rec,
+ int did_repair)
+{
+ int ret;
+ int err = 0;
+ struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
+
+ set_state_private(failure_tree, rec->start, 0);
+ ret = clear_extent_bits(failure_tree, rec->start,
+ rec->start + rec->len - 1,
+ EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
+ if (ret)
+ err = ret;
+
+ if (did_repair) {
+ ret = clear_extent_bits(&BTRFS_I(inode)->io_tree, rec->start,
+ rec->start + rec->len - 1,
+ EXTENT_DAMAGED, GFP_NOFS);
+ if (ret && !err)
+ err = ret;
+ }
+
+ kfree(rec);
+ return err;
+}
+
+static void repair_io_failure_callback(struct bio *bio, int err)
+{
+ complete(bio->bi_private);
+}
+
+/*
+ * this bypasses the standard btrfs submit functions deliberately, as
+ * the standard behavior is to write all copies in a raid setup. here we only
+ * want to write the one bad copy. so we do the mapping for ourselves and issue
+ * submit_bio directly.
+ * to avoid any synchonization issues, wait for the data after writing, which
+ * actually prevents the read that triggered the error from finishing.
+ * currently, there can be no more than two copies of every data bit. thus,
+ * exactly one rewrite is required.
+ */
+int repair_io_failure(struct btrfs_mapping_tree *map_tree, u64 start,
+ u64 length, u64 logical, struct page *page,
+ int mirror_num)
+{
+ struct bio *bio;
+ struct btrfs_device *dev;
+ DECLARE_COMPLETION_ONSTACK(compl);
+ u64 map_length = 0;
+ u64 sector;
+ struct btrfs_bio *bbio = NULL;
+ int ret;
+
+ BUG_ON(!mirror_num);
+
+ bio = bio_alloc(GFP_NOFS, 1);
+ if (!bio)
+ return -EIO;
+ bio->bi_private = &compl;
+ bio->bi_end_io = repair_io_failure_callback;
+ bio->bi_size = 0;
+ map_length = length;
+
+ ret = btrfs_map_block(map_tree, WRITE, logical,
+ &map_length, &bbio, mirror_num);
+ if (ret) {
+ bio_put(bio);
+ return -EIO;
+ }
+ BUG_ON(mirror_num != bbio->mirror_num);
+ sector = bbio->stripes[mirror_num-1].physical >> 9;
+ bio->bi_sector = sector;
+ dev = bbio->stripes[mirror_num-1].dev;
+ kfree(bbio);
+ if (!dev || !dev->bdev || !dev->writeable) {
+ bio_put(bio);
+ return -EIO;
+ }
+ bio->bi_bdev = dev->bdev;
+ bio_add_page(bio, page, length, start-page_offset(page));
+ submit_bio(WRITE_SYNC, bio);
+ wait_for_completion(&compl);
+
+ if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+ /* try to remap that extent elsewhere? */
+ bio_put(bio);
+ return -EIO;
+ }
+
+ printk(KERN_INFO "btrfs read error corrected: ino %lu off %llu (dev %s "
+ "sector %llu)\n", page->mapping->host->i_ino, start,
+ dev->name, sector);
+
+ bio_put(bio);
+ return 0;
+}
+
+/*
+ * each time an IO finishes, we do a fast check in the IO failure tree
+ * to see if we need to process or clean up an io_failure_record
+ */
+static int clean_io_failure(u64 start, struct page *page)
+{
+ u64 private;
+ u64 private_failure;
+ struct io_failure_record *failrec;
+ struct btrfs_mapping_tree *map_tree;
+ struct extent_state *state;
+ int num_copies;
+ int did_repair = 0;
+ int ret;
+ struct inode *inode = page->mapping->host;
+
+ private = 0;
+ ret = count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
+ (u64)-1, 1, EXTENT_DIRTY, 0);
+ if (!ret)
+ return 0;
+
+ ret = get_state_private(&BTRFS_I(inode)->io_failure_tree, start,
+ &private_failure);
+ if (ret)
+ return 0;
+
+ failrec = (struct io_failure_record *)(unsigned long) private_failure;
+ BUG_ON(!failrec->this_mirror);
+
+ if (failrec->in_validation) {
+ /* there was no real error, just free the record */
+ pr_debug("clean_io_failure: freeing dummy error at %llu\n",
+ failrec->start);
+ did_repair = 1;
+ goto out;
+ }
+
+ spin_lock(&BTRFS_I(inode)->io_tree.lock);
+ state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
+ failrec->start,
+ EXTENT_LOCKED);
+ spin_unlock(&BTRFS_I(inode)->io_tree.lock);
+
+ if (state && state->start == failrec->start) {
+ map_tree = &BTRFS_I(inode)->root->fs_info->mapping_tree;
+ num_copies = btrfs_num_copies(map_tree, failrec->logical,
+ failrec->len);
+ if (num_copies > 1) {
+ ret = repair_io_failure(map_tree, start, failrec->len,
+ failrec->logical, page,
+ failrec->failed_mirror);
+ did_repair = !ret;
+ }
+ }
+
+out:
+ if (!ret)
+ ret = free_io_failure(inode, failrec, did_repair);
+
+ return ret;
+}
+
+/*
+ * this is a generic handler for readpage errors (default
+ * readpage_io_failed_hook). if other copies exist, read those and write back
+ * good data to the failed position. does not investigate in remapping the
+ * failed extent elsewhere, hoping the device will be smart enough to do this as
+ * needed
+ */
+
+static int bio_readpage_error(struct bio *failed_bio, struct page *page,
+ u64 start, u64 end, int failed_mirror,
+ struct extent_state *state)
+{
+ struct io_failure_record *failrec = NULL;
+ u64 private;
+ struct extent_map *em;
+ struct inode *inode = page->mapping->host;
+ struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
+ struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
+ struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+ struct bio *bio;
+ int num_copies;
+ int ret;
+ int read_mode;
+ u64 logical;
+
+ BUG_ON(failed_bio->bi_rw & REQ_WRITE);
+
+ ret = get_state_private(failure_tree, start, &private);
+ if (ret) {
+ failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
+ if (!failrec)
+ return -ENOMEM;
+ failrec->start = start;
+ failrec->len = end - start + 1;
+ failrec->this_mirror = 0;
+ failrec->bio_flags = 0;
+ failrec->in_validation = 0;
+
+ read_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree, start, failrec->len);
+ if (!em) {
+ read_unlock(&em_tree->lock);
+ kfree(failrec);
+ return -EIO;
+ }
+
+ if (em->start > start || em->start + em->len < start) {
+ free_extent_map(em);
+ em = NULL;
+ }
+ read_unlock(&em_tree->lock);
+
+ if (!em || IS_ERR(em)) {
+ kfree(failrec);
+ return -EIO;
+ }
+ logical = start - em->start;
+ logical = em->block_start + logical;
+ if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+ logical = em->block_start;
+ failrec->bio_flags = EXTENT_BIO_COMPRESSED;
+ extent_set_compress_type(&failrec->bio_flags,
+ em->compress_type);
+ }
+ pr_debug("bio_readpage_error: (new) logical=%llu, start=%llu, "
+ "len=%llu\n", logical, start, failrec->len);
+ failrec->logical = logical;
+ free_extent_map(em);
+
+ /* set the bits in the private failure tree */
+ ret = set_extent_bits(failure_tree, start, end,
+ EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
+ if (ret >= 0)
+ ret = set_state_private(failure_tree, start,
+ (u64)(unsigned long)failrec);
+ /* set the bits in the inode's tree */
+ if (ret >= 0)
+ ret = set_extent_bits(tree, start, end, EXTENT_DAMAGED,
+ GFP_NOFS);
+ if (ret < 0) {
+ kfree(failrec);
+ return ret;
+ }
+ } else {
+ failrec = (struct io_failure_record *)(unsigned long)private;
+ pr_debug("bio_readpage_error: (found) logical=%llu, "
+ "start=%llu, len=%llu, validation=%d\n",
+ failrec->logical, failrec->start, failrec->len,
+ failrec->in_validation);
+ /*
+ * when data can be on disk more than twice, add to failrec here
+ * (e.g. with a list for failed_mirror) to make
+ * clean_io_failure() clean all those errors at once.
+ */
+ }
+ num_copies = btrfs_num_copies(
+ &BTRFS_I(inode)->root->fs_info->mapping_tree,
+ failrec->logical, failrec->len);
+ if (num_copies == 1) {
+ /*
+ * we only have a single copy of the data, so don't bother with
+ * all the retry and error correction code that follows. no
+ * matter what the error is, it is very likely to persist.
+ */
+ pr_debug("bio_readpage_error: cannot repair, num_copies == 1. "
+ "state=%p, num_copies=%d, next_mirror %d, "
+ "failed_mirror %d\n", state, num_copies,
+ failrec->this_mirror, failed_mirror);
+ free_io_failure(inode, failrec, 0);
+ return -EIO;
+ }
+
+ if (!state) {
+ spin_lock(&tree->lock);
+ state = find_first_extent_bit_state(tree, failrec->start,
+ EXTENT_LOCKED);
+ if (state && state->start != failrec->start)
+ state = NULL;
+ spin_unlock(&tree->lock);
+ }
+
+ /*
+ * there are two premises:
+ * a) deliver good data to the caller
+ * b) correct the bad sectors on disk
+ */
+ if (failed_bio->bi_vcnt > 1) {
+ /*
+ * to fulfill b), we need to know the exact failing sectors, as
+ * we don't want to rewrite any more than the failed ones. thus,
+ * we need separate read requests for the failed bio
+ *
+ * if the following BUG_ON triggers, our validation request got
+ * merged. we need separate requests for our algorithm to work.
+ */
+ BUG_ON(failrec->in_validation);
+ failrec->in_validation = 1;
+ failrec->this_mirror = failed_mirror;
+ read_mode = READ_SYNC | REQ_FAILFAST_DEV;
+ } else {
+ /*
+ * we're ready to fulfill a) and b) alongside. get a good copy
+ * of the failed sector and if we succeed, we have setup
+ * everything for repair_io_failure to do the rest for us.
+ */
+ if (failrec->in_validation) {
+ BUG_ON(failrec->this_mirror != failed_mirror);
+ failrec->in_validation = 0;
+ failrec->this_mirror = 0;
+ }
+ failrec->failed_mirror = failed_mirror;
+ failrec->this_mirror++;
+ if (failrec->this_mirror == failed_mirror)
+ failrec->this_mirror++;
+ read_mode = READ_SYNC;
+ }
+
+ if (!state || failrec->this_mirror > num_copies) {
+ pr_debug("bio_readpage_error: (fail) state=%p, num_copies=%d, "
+ "next_mirror %d, failed_mirror %d\n", state,
+ num_copies, failrec->this_mirror, failed_mirror);
+ free_io_failure(inode, failrec, 0);
+ return -EIO;
+ }
+
+ bio = bio_alloc(GFP_NOFS, 1);
+ bio->bi_private = state;
+ bio->bi_end_io = failed_bio->bi_end_io;
+ bio->bi_sector = failrec->logical >> 9;
+ bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+ bio->bi_size = 0;
+
+ bio_add_page(bio, page, failrec->len, start - page_offset(page));
+
+ pr_debug("bio_readpage_error: submitting new read[%#x] to "
+ "this_mirror=%d, num_copies=%d, in_validation=%d\n", read_mode,
+ failrec->this_mirror, num_copies, failrec->in_validation);
+
+ tree->ops->submit_bio_hook(inode, read_mode, bio, failrec->this_mirror,
+ failrec->bio_flags, 0);
+ return 0;
+}
+
/* lots and lots of room for performance fixes in the end_bio funcs */
/*
@@ -1697,6 +2060,9 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
struct extent_state *cached = NULL;
struct extent_state *state;
+ pr_debug("end_bio_extent_readpage: bi_vcnt=%d, idx=%d, err=%d, "
+ "mirror=%ld\n", bio->bi_vcnt, bio->bi_idx, err,
+ (long int)bio->bi_bdev);
tree = &BTRFS_I(page->mapping->host)->io_tree;
start = ((u64)page->index << PAGE_CACHE_SHIFT) +
@@ -1727,11 +2093,19 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
state);
if (ret)
uptodate = 0;
+ else
+ clean_io_failure(start, page);
}
- if (!uptodate && tree->ops &&
- tree->ops->readpage_io_failed_hook) {
- ret = tree->ops->readpage_io_failed_hook(bio, page,
- start, end, NULL);
+ if (!uptodate) {
+ u64 failed_mirror;
+ failed_mirror = (u64)bio->bi_bdev;
+ if (tree->ops && tree->ops->readpage_io_failed_hook)
+ ret = tree->ops->readpage_io_failed_hook(
+ bio, page, start, end,
+ failed_mirror, NULL);
+ else
+ ret = bio_readpage_error(bio, page, start, end,
+ failed_mirror, NULL);
if (ret == 0) {
uptodate =
test_bit(BIO_UPTODATE, &bio->bi_flags);
@@ -1811,6 +2185,7 @@ static int submit_one_bio(int rw, struct bio *bio, int mirror_num,
mirror_num, bio_flags, start);
else
submit_bio(rw, bio);
+
if (bio_flagged(bio, BIO_EOPNOTSUPP))
ret = -EOPNOTSUPP;
bio_put(bio);
@@ -2926,7 +3301,7 @@ out:
return ret;
}
-static inline struct page *extent_buffer_page(struct extent_buffer *eb,
+inline struct page *extent_buffer_page(struct extent_buffer *eb,
unsigned long i)
{
struct page *p;
@@ -2951,7 +3326,7 @@ static inline struct page *extent_buffer_page(struct extent_buffer *eb,
return p;
}
-static inline unsigned long num_extent_pages(u64 start, u64 len)
+inline unsigned long num_extent_pages(u64 start, u64 len)
{
return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
(start >> PAGE_CACHE_SHIFT);
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 435d454b992..a8e20b67292 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -68,7 +68,7 @@ struct extent_io_ops {
unsigned long bio_flags);
int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
int (*readpage_io_failed_hook)(struct bio *bio, struct page *page,
- u64 start, u64 end,
+ u64 start, u64 end, u64 failed_mirror,
struct extent_state *state);
int (*writepage_io_failed_hook)(struct bio *bio, struct page *page,
u64 start, u64 end,
@@ -252,6 +252,8 @@ void free_extent_buffer(struct extent_buffer *eb);
int read_extent_buffer_pages(struct extent_io_tree *tree,
struct extent_buffer *eb, u64 start, int wait,
get_extent_t *get_extent, int mirror_num);
+unsigned long num_extent_pages(u64 start, u64 len);
+struct page *extent_buffer_page(struct extent_buffer *eb, unsigned long i);
static inline void extent_buffer_get(struct extent_buffer *eb)
{
@@ -301,4 +303,10 @@ int extent_clear_unlock_delalloc(struct inode *inode,
struct bio *
btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
gfp_t gfp_flags);
+
+struct btrfs_mapping_tree;
+
+int repair_io_failure(struct btrfs_mapping_tree *map_tree, u64 start,
+ u64 length, u64 logical, struct page *page,
+ int mirror_num);
#endif
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 936a6fabaa9..9327f45434e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -45,10 +45,10 @@
#include "btrfs_inode.h"
#include "ioctl.h"
#include "print-tree.h"
-#include "volumes.h"
#include "ordered-data.h"
#include "xattr.h"
#include "tree-log.h"
+#include "volumes.h"
#include "compression.h"
#include "locking.h"
#include "free-space-cache.h"
@@ -1819,153 +1819,9 @@ static int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end,
}
/*
- * When IO fails, either with EIO or csum verification fails, we
- * try other mirrors that might have a good copy of the data. This
- * io_failure_record is used to record state as we go through all the
- * mirrors. If another mirror has good data, the page is set up to date
- * and things continue. If a good mirror can't be found, the original
- * bio end_io callback is called to indicate things have failed.
- */
-struct io_failure_record {
- struct page *page;
- u64 start;
- u64 len;
- u64 logical;
- unsigned long bio_flags;
- int last_mirror;
-};
-
-static int btrfs_io_failed_hook(struct bio *failed_bio,
- struct page *page, u64 start, u64 end,
- struct extent_state *state)
-{
- struct io_failure_record *failrec = NULL;
- u64 private;
- struct extent_map *em;
- struct inode *inode = page->mapping->host;
- struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
- struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
- struct bio *bio;
- int num_copies;
- int ret;
- int rw;
- u64 logical;
-
- ret = get_state_private(failure_tree, start, &private);
- if (ret) {
- failrec = kmalloc(sizeof(*failrec), GFP_NOFS);
- if (!failrec)
- return -ENOMEM;
- failrec->start = start;
- failrec->len = end - start + 1;
- failrec->last_mirror = 0;
- failrec->bio_flags = 0;
-
- read_lock(&em_tree->lock);
- em = lookup_extent_mapping(em_tree, start, failrec->len);
- if (em->start > start || em->start + em->len < start) {
- free_extent_map(em);
- em = NULL;
- }
- read_unlock(&em_tree->lock);
-
- if (IS_ERR_OR_NULL(em)) {
- kfree(failrec);
- return -EIO;
- }
- logical = start - em->start;
- logical = em->block_start + logical;
- if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
- logical = em->block_start;
- failrec->bio_flags = EXTENT_BIO_COMPRESSED;
- extent_set_compress_type(&failrec->bio_flags,
- em->compress_type);
- }
- failrec->logical = logical;
- free_extent_map(em);
- set_extent_bits(failure_tree, start, end, EXTENT_LOCKED |
- EXTENT_DIRTY, GFP_NOFS);
- set_state_private(failure_tree, start,
- (u64)(unsigned long)failrec);
- } else {
- failrec = (struct io_failure_record *)(unsigned long)private;
- }
- num_copies = btrfs_num_copies(
- &BTRFS_I(inode)->root->fs_info->mapping_tree,
- failrec->logical, failrec->len);
- failrec->last_mirror++;
- if (!state) {
- spin_lock(&BTRFS_I(inode)->io_tree.lock);
- state = find_first_extent_bit_state(&BTRFS_I(inode)->io_tree,
- failrec->start,
- EXTENT_LOCKED);
- if (state && state->start != failrec->start)
- state = NULL;
- spin_unlock(&BTRFS_I(inode)->io_tree.lock);
- }
- if (!state || failrec->last_mirror > num_copies) {
- set_state_private(failure_tree, failrec->start, 0);
- clear_extent_bits(failure_tree, failrec->start,
- failrec->start + failrec->len - 1,
- EXTENT_LOCKED | EXTENT_DIRTY, GFP_NOFS);
- kfree(failrec);
- return -EIO;
- }
- bio = bio_alloc(GFP_NOFS, 1);
- bio->bi_private = state;
- bio->bi_end_io = failed_bio->bi_end_io;
- bio->bi_sector = failrec->logical >> 9;
- bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
- bio->bi_size = 0;
-
- bio_add_page(bio, page, failrec->len, start - page_offset(page));
- if (failed_bio->bi_rw & REQ_WRITE)
- rw = WRITE;
- else
- rw = READ;
-
- ret = BTRFS_I(inode)->io_tree.ops->submit_bio_hook(inode, rw, bio,
- failrec->last_mirror,
- failrec->bio_flags, 0);
- return ret;
-}
-
-/*
- * each time an IO finishes, we do a fast check in the IO failure tree
- * to see if we need to process or clean up an io_failure_record
- */
-static int btrfs_clean_io_failures(struct inode *inode, u64 start)
-{
- u64 private;
- u64 private_failure;
- struct io_failure_record *failure;
- int ret;
-
- private = 0;
- if (count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
- (u64)-1, 1, EXTENT_DIRTY, 0)) {
- ret = get_state_private(&BTRFS_I(inode)->io_failure_tree,
- start, &private_failure);
- if (ret == 0) {
- failure = (struct io_failure_record *)(unsigned long)
- private_failure;
- set_state_private(&BTRFS_I(inode)->io_failure_tree,
- failure->start, 0);
- clear_extent_bits(&BTRFS_I(inode)->io_failure_tree,
- failure->start,
- failure->start + failure->len - 1,
- EXTENT_DIRTY | EXTENT_LOCKED,
- GFP_NOFS);
- kfree(failure);
- }
- }
- return 0;
-}
-
-/*
* when reads are done, we need to check csums to verify the data is correct
- * if there's a match, we allow the bio to finish. If not, we go through
- * the io_failure_record routines to find good copies
+ * if there's a match, we allow the bio to finish. If not, the code in
+ * extent_io.c will try to find good copies for us.
*/
static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
struct extent_state *state)
@@ -2011,10 +1867,6 @@ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
kunmap_atomic(kaddr, KM_USER0);
good:
- /* if the io failure tree for this inode is non-empty,
- * check to see if we've recovered from a failed IO
- */
- btrfs_clean_io_failures(inode, start);
return 0;
zeroit:
@@ -7420,7 +7272,6 @@ static struct extent_io_ops btrfs_extent_io_ops = {
.readpage_end_io_hook = btrfs_readpage_end_io_hook,
.writepage_end_io_hook = btrfs_writepage_end_io_hook,
.writepage_start_hook = btrfs_writepage_start_hook,
- .readpage_io_failed_hook = btrfs_io_failed_hook,
.set_bit_hook = btrfs_set_bit_hook,
.clear_bit_hook = btrfs_clear_bit_hook,
.merge_extent_hook = btrfs_merge_extent_hook,