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authorYan Zheng <zheng.yan@oracle.com>2008-10-30 14:19:50 -0400
committerChris Mason <chris.mason@oracle.com>2008-10-30 14:19:50 -0400
commit6643558db29006825dbb10012b3f8890aca4bcd5 (patch)
tree0c0f4f7a0011749cda998431828cb9161747b51a
parent9036c10208e1fc496cef7692ba66a78699b360dc (diff)
Btrfs: Fix bookend extent race v2
When dropping middle part of an extent, btrfs_drop_extents truncates the extent at first, then inserts a bookend extent. Since truncation and insertion can't be done atomically, there is a small period that the bookend extent isn't in the tree. This causes problem for functions that search the tree for file extent item. The way to fix this is lock the range of the bookend extent before truncation. Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
-rw-r--r--fs/btrfs/extent-tree.c28
-rw-r--r--fs/btrfs/extent_io.c6
-rw-r--r--fs/btrfs/file.c31
-rw-r--r--fs/btrfs/inode.c10
4 files changed, 43 insertions, 32 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index fada9c22a02..535cee47fcf 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3379,11 +3379,13 @@ static int noinline relocate_data_extent(struct inode *reloc_inode,
struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
struct extent_map_tree *em_tree = &BTRFS_I(reloc_inode)->extent_tree;
struct extent_map *em;
+ u64 start = extent_key->objectid - offset;
+ u64 end = start + extent_key->offset - 1;
em = alloc_extent_map(GFP_NOFS);
BUG_ON(!em || IS_ERR(em));
- em->start = extent_key->objectid - offset;
+ em->start = start;
em->len = extent_key->offset;
em->block_len = extent_key->offset;
em->block_start = extent_key->objectid;
@@ -3391,7 +3393,7 @@ static int noinline relocate_data_extent(struct inode *reloc_inode,
set_bit(EXTENT_FLAG_PINNED, &em->flags);
/* setup extent map to cheat btrfs_readpage */
- mutex_lock(&BTRFS_I(reloc_inode)->extent_mutex);
+ lock_extent(&BTRFS_I(reloc_inode)->io_tree, start, end, GFP_NOFS);
while (1) {
int ret;
spin_lock(&em_tree->lock);
@@ -3401,13 +3403,11 @@ static int noinline relocate_data_extent(struct inode *reloc_inode,
free_extent_map(em);
break;
}
- btrfs_drop_extent_cache(reloc_inode, em->start,
- em->start + em->len - 1, 0);
+ btrfs_drop_extent_cache(reloc_inode, start, end, 0);
}
- mutex_unlock(&BTRFS_I(reloc_inode)->extent_mutex);
+ unlock_extent(&BTRFS_I(reloc_inode)->io_tree, start, end, GFP_NOFS);
- return relocate_inode_pages(reloc_inode, extent_key->objectid - offset,
- extent_key->offset);
+ return relocate_inode_pages(reloc_inode, start, extent_key->offset);
}
struct btrfs_ref_path {
@@ -3831,7 +3831,6 @@ next:
* the file extent item was modified by someone
* before the extent got locked.
*/
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
lock_end, GFP_NOFS);
extent_locked = 0;
@@ -3896,8 +3895,12 @@ next:
lock_start = key.offset;
lock_end = lock_start + num_bytes - 1;
} else {
- BUG_ON(lock_start != key.offset);
- BUG_ON(lock_end - lock_start + 1 < num_bytes);
+ if (lock_start > key.offset ||
+ lock_end + 1 < key.offset + num_bytes) {
+ unlock_extent(&BTRFS_I(inode)->io_tree,
+ lock_start, lock_end, GFP_NOFS);
+ extent_locked = 0;
+ }
}
if (!inode) {
@@ -3951,7 +3954,6 @@ next:
if (ordered)
btrfs_put_ordered_extent(ordered);
- mutex_lock(&BTRFS_I(inode)->extent_mutex);
extent_locked = 1;
continue;
}
@@ -4073,7 +4075,6 @@ next:
}
if (extent_locked) {
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
lock_end, GFP_NOFS);
extent_locked = 0;
@@ -4091,7 +4092,6 @@ out:
if (inode) {
mutex_unlock(&inode->i_mutex);
if (extent_locked) {
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
lock_end, GFP_NOFS);
}
@@ -4180,10 +4180,8 @@ static int noinline invalidate_extent_cache(struct btrfs_root *root,
lock_extent(&BTRFS_I(inode)->io_tree, key.offset,
key.offset + num_bytes - 1, GFP_NOFS);
- mutex_lock(&BTRFS_I(inode)->extent_mutex);
btrfs_drop_extent_cache(inode, key.offset,
key.offset + num_bytes - 1, 1);
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
unlock_extent(&BTRFS_I(inode)->io_tree, key.offset,
key.offset + num_bytes - 1, GFP_NOFS);
cond_resched();
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 7503bd46819..65a0583027e 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -946,8 +946,12 @@ int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
&failed_start, mask);
- if (err == -EEXIST)
+ if (err == -EEXIST) {
+ if (failed_start > start)
+ clear_extent_bit(tree, start, failed_start - 1,
+ EXTENT_LOCKED, 1, 0, mask);
return 0;
+ }
return 1;
}
EXPORT_SYMBOL(try_lock_extent);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index b8a7637e14a..1a0510ad030 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -364,6 +364,7 @@ int noinline btrfs_drop_extents(struct btrfs_trans_handle *trans,
u64 start, u64 end, u64 inline_limit, u64 *hint_byte)
{
u64 extent_end = 0;
+ u64 locked_end = end;
u64 search_start = start;
u64 leaf_start;
u64 ram_bytes = 0;
@@ -479,12 +480,6 @@ next_slot:
goto next_slot;
}
- if (found_inline) {
- u64 mask = root->sectorsize - 1;
- search_start = (extent_end + mask) & ~mask;
- } else
- search_start = extent_end;
-
if (end <= extent_end && start >= key.offset && found_inline)
*hint_byte = EXTENT_MAP_INLINE;
@@ -501,6 +496,26 @@ next_slot:
if (found_inline && start <= key.offset)
keep = 1;
}
+
+ if (bookend && found_extent && locked_end < extent_end) {
+ ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
+ locked_end, extent_end - 1, GFP_NOFS);
+ if (!ret) {
+ btrfs_release_path(root, path);
+ lock_extent(&BTRFS_I(inode)->io_tree,
+ locked_end, extent_end - 1, GFP_NOFS);
+ locked_end = extent_end;
+ continue;
+ }
+ locked_end = extent_end;
+ }
+
+ if (found_inline) {
+ u64 mask = root->sectorsize - 1;
+ search_start = (extent_end + mask) & ~mask;
+ } else
+ search_start = extent_end;
+
/* truncate existing extent */
if (start > key.offset) {
u64 new_num;
@@ -638,6 +653,10 @@ next_slot:
}
out:
btrfs_free_path(path);
+ if (locked_end > end) {
+ unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
+ GFP_NOFS);
+ }
btrfs_check_file(root, inode);
return ret;
}
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8254d6fa691..e8511d14b11 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -246,7 +246,6 @@ static int cow_file_range_inline(struct btrfs_trans_handle *trans,
return 1;
}
- mutex_lock(&BTRFS_I(inode)->extent_mutex);
ret = btrfs_drop_extents(trans, root, inode, start,
aligned_end, aligned_end, &hint_byte);
BUG_ON(ret);
@@ -258,7 +257,6 @@ static int cow_file_range_inline(struct btrfs_trans_handle *trans,
compressed_pages);
BUG_ON(ret);
btrfs_drop_extent_cache(inode, start, aligned_end, 0);
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
return 0;
}
@@ -437,9 +435,7 @@ again:
BUG_ON(disk_num_bytes >
btrfs_super_total_bytes(&root->fs_info->super_copy));
- mutex_lock(&BTRFS_I(inode)->extent_mutex);
btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0);
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
while(disk_num_bytes > 0) {
unsigned long min_bytes;
@@ -477,8 +473,6 @@ again:
em->block_start = ins.objectid;
em->block_len = ins.offset;
em->bdev = root->fs_info->fs_devices->latest_bdev;
-
- mutex_lock(&BTRFS_I(inode)->extent_mutex);
set_bit(EXTENT_FLAG_PINNED, &em->flags);
if (will_compress)
@@ -495,7 +489,6 @@ again:
btrfs_drop_extent_cache(inode, start,
start + ram_size - 1, 0);
}
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
cur_alloc_size = ins.offset;
ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
@@ -1016,8 +1009,6 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
INIT_LIST_HEAD(&list);
- mutex_lock(&BTRFS_I(inode)->extent_mutex);
-
ret = btrfs_drop_extents(trans, root, inode,
ordered_extent->file_offset,
ordered_extent->file_offset +
@@ -1059,7 +1050,6 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
btrfs_drop_extent_cache(inode, ordered_extent->file_offset,
ordered_extent->file_offset +
ordered_extent->len - 1, 0);
- mutex_unlock(&BTRFS_I(inode)->extent_mutex);
ins.objectid = ordered_extent->start;
ins.offset = ordered_extent->disk_len;