Btrfs: Handle checksumming errors while reading data blocks

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

1 files changed, 113 insertions, 1 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8c2d5d036bd6..48f1d1b96450 100644
--- 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,
 };