Btrfs: Handle checksumming errors while reading data blocks

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 9b9db9c..fe6ef8e 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -29,6 +29,7 @@ struct btrfs_inode {
        struct btrfs_key location;
        struct extent_map_tree extent_tree;
        struct extent_io_tree io_tree;
+       struct extent_io_tree io_failure_tree;
        struct inode vfs_inode;
 
        u64 ordered_trans;

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 2f15937..866460c 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1534,6 +1534,15 @@ static int end_bio_extent_readpage(struct bio *bio,
                        if (ret)
                                uptodate = 0;
                }
+               if (!uptodate && tree->ops &&
+                   tree->ops->readpage_io_failed_hook) {
+                       ret = tree->ops->readpage_io_failed_hook(bio, page,
+                                                        start, end, state);
+                       if (ret == 0) {
+                               state = NULL;
+                               continue;
+                       }
+               }
 
                spin_lock_irqsave(&tree->lock, flags);
                if (!state || state->end != end) {

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 8d6b8a1..b47859c 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -32,6 +32,9 @@ struct extent_io_ops {
        int (*merge_bio_hook)(struct page *page, unsigned long offset,
                              size_t size, struct bio *bio);
        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,
+                                      struct extent_state *state);
        int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end,
                                    struct extent_state *state);
        void (*writepage_end_io_hook)(struct page *page, u64 start, u64 end,

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8c2d5d0..48f1d1b 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -385,6 +385,86 @@ out:
        return ret;
 }
 
+struct io_failure_record {
+       struct page *page;
+       u64 start;
+       u64 len;
+       u64 logical;
+       int last_mirror;
+};
+
+int btrfs_readpage_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 bio *bio;
+       int num_copies;
+       int ret;
+       u64 logical;
+
+       ret = get_state_private(failure_tree, start, &private);
+       if (ret) {
+               size_t pg_offset = start - page_offset(page);
+               failrec = kmalloc(sizeof(*failrec), GFP_NOFS);
+               if (!failrec)
+                       return -ENOMEM;
+               failrec->start = start;
+               failrec->len = end - start + 1;
+               failrec->last_mirror = 0;
+
+               em = btrfs_get_extent(inode, NULL, pg_offset, start,
+                                     failrec->len, 0);
+
+               if (!em || IS_ERR(em)) {
+                       kfree(failrec);
+                       return -EIO;
+               }
+               logical = start - em->start;
+               logical = em->block_start + logical;
+               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)failrec);
+       } else {
+               failrec = (struct io_failure_record *)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_irq(&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_irq(&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 = failed_bio->bi_bdev;
+       bio_add_page(bio, page, failrec->len, start - page_offset(page));
+       btrfs_submit_bio_hook(inode, READ, bio, failrec->last_mirror);
+       return 0;
+}
+
 int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
                               struct extent_state *state)
 {
@@ -419,6 +499,29 @@ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
        }
        kunmap_atomic(kaddr, KM_IRQ0);
        local_irq_restore(flags);
+
+       /* if the io failure tree for this inode is non-empty,
+        * check to see if we've recovered from a failed IO
+        */
+       private = 0;
+       if (count_range_bits(&BTRFS_I(inode)->io_failure_tree, &private,
+                            (u64)-1, 1, EXTENT_DIRTY)) {
+               u64 private_failure;
+               struct io_failure_record *failure;
+               ret = get_state_private(&BTRFS_I(inode)->io_failure_tree,
+                                       start, &private_failure);
+               if (ret == 0) {
+                       failure = (struct io_failure_record *)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;
 
 zeroit:
@@ -429,7 +532,7 @@ zeroit:
        flush_dcache_page(page);
        kunmap_atomic(kaddr, KM_IRQ0);
        local_irq_restore(flags);
-       return 0;
+       return -EIO;
 }
 
 void btrfs_read_locked_inode(struct inode *inode)
@@ -1271,6 +1374,8 @@ static int btrfs_init_locked_inode(struct inode *inode, void *p)
        extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
        extent_io_tree_init(&BTRFS_I(inode)->io_tree,
                             inode->i_mapping, GFP_NOFS);
+       extent_io_tree_init(&BTRFS_I(inode)->io_failure_tree,
+                            inode->i_mapping, GFP_NOFS);
        return 0;
 }
 
@@ -1578,6 +1683,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
        extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
        extent_io_tree_init(&BTRFS_I(inode)->io_tree,
                             inode->i_mapping, GFP_NOFS);
+       extent_io_tree_init(&BTRFS_I(inode)->io_failure_tree,
+                            inode->i_mapping, GFP_NOFS);
        BTRFS_I(inode)->delalloc_bytes = 0;
        BTRFS_I(inode)->root = root;
 
@@ -1803,6 +1910,8 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
                extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
                extent_io_tree_init(&BTRFS_I(inode)->io_tree,
                                     inode->i_mapping, GFP_NOFS);
+               extent_io_tree_init(&BTRFS_I(inode)->io_failure_tree,
+                                    inode->i_mapping, GFP_NOFS);
                BTRFS_I(inode)->delalloc_bytes = 0;
                BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
        }
@@ -2972,6 +3081,8 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
                extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
                extent_io_tree_init(&BTRFS_I(inode)->io_tree,
                                     inode->i_mapping, GFP_NOFS);
+               extent_io_tree_init(&BTRFS_I(inode)->io_failure_tree,
+                                    inode->i_mapping, GFP_NOFS);
                BTRFS_I(inode)->delalloc_bytes = 0;
                BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
        }
@@ -3070,6 +3181,7 @@ static struct extent_io_ops btrfs_extent_io_ops = {
        .merge_bio_hook = btrfs_merge_bio_hook,
        .readpage_io_hook = btrfs_readpage_io_hook,
        .readpage_end_io_hook = btrfs_readpage_end_io_hook,
+       .readpage_io_failed_hook = btrfs_readpage_io_failed_hook,
        .set_bit_hook = btrfs_set_bit_hook,
        .clear_bit_hook = btrfs_clear_bit_hook,
 };