[064/111] Btrfs: Fix race in btrfs_mark_extent_written
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From: Greg KH on 11 Aug 2010 20:40 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Yan, Zheng <zheng.yan(a)oracle.com> commit 6c7d54ac87f338c479d9729e8392eca3f76e11e1 upstream. Fix bug reported by Johannes Hirte. The reason of that bug is btrfs_del_items is called after btrfs_duplicate_item and btrfs_del_items triggers tree balance. The fix is check that case and call btrfs_search_slot when needed. Signed-off-by: Yan Zheng <zheng.yan(a)oracle.com> Signed-off-by: Chris Mason <chris.mason(a)oracle.com> Acked-by: Jeff Mahoney <jeffm(a)suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- fs/btrfs/file.c | 100 ++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 80 insertions(+), 20 deletions(-) --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -506,7 +506,8 @@ next_slot: } static int extent_mergeable(struct extent_buffer *leaf, int slot, - u64 objectid, u64 bytenr, u64 *start, u64 *end) + u64 objectid, u64 bytenr, u64 orig_offset, + u64 *start, u64 *end) { struct btrfs_file_extent_item *fi; struct btrfs_key key; @@ -522,6 +523,7 @@ static int extent_mergeable(struct exten fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item); if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG || btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr || + btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset || btrfs_file_extent_compression(leaf, fi) || btrfs_file_extent_encryption(leaf, fi) || btrfs_file_extent_other_encoding(leaf, fi)) @@ -561,6 +563,7 @@ int btrfs_mark_extent_written(struct btr u64 split; int del_nr = 0; int del_slot = 0; + int recow; int ret; btrfs_drop_extent_cache(inode, start, end - 1, 0); @@ -568,6 +571,7 @@ int btrfs_mark_extent_written(struct btr path = btrfs_alloc_path(); BUG_ON(!path); again: + recow = 0; split = start; key.objectid = inode->i_ino; key.type = BTRFS_EXTENT_DATA_KEY; @@ -591,12 +595,60 @@ again: bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi); orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi); + memcpy(&new_key, &key, sizeof(new_key)); + + if (start == key.offset && end < extent_end) { + other_start = 0; + other_end = start; + if (extent_mergeable(leaf, path->slots[0] - 1, + inode->i_ino, bytenr, orig_offset, + &other_start, &other_end)) { + new_key.offset = end; + btrfs_set_item_key_safe(trans, root, path, &new_key); + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + btrfs_set_file_extent_num_bytes(leaf, fi, + extent_end - end); + btrfs_set_file_extent_offset(leaf, fi, + end - orig_offset); + fi = btrfs_item_ptr(leaf, path->slots[0] - 1, + struct btrfs_file_extent_item); + btrfs_set_file_extent_num_bytes(leaf, fi, + end - other_start); + btrfs_mark_buffer_dirty(leaf); + goto out; + } + } + + if (start > key.offset && end == extent_end) { + other_start = end; + other_end = 0; + if (extent_mergeable(leaf, path->slots[0] + 1, + inode->i_ino, bytenr, orig_offset, + &other_start, &other_end)) { + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + btrfs_set_file_extent_num_bytes(leaf, fi, + start - key.offset); + path->slots[0]++; + new_key.offset = start; + btrfs_set_item_key_safe(trans, root, path, &new_key); + + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + btrfs_set_file_extent_num_bytes(leaf, fi, + other_end - start); + btrfs_set_file_extent_offset(leaf, fi, + start - orig_offset); + btrfs_mark_buffer_dirty(leaf); + goto out; + } + } while (start > key.offset || end < extent_end) { if (key.offset == start) split = end; - memcpy(&new_key, &key, sizeof(new_key)); new_key.offset = split; ret = btrfs_duplicate_item(trans, root, path, &new_key); if (ret == -EAGAIN) { @@ -631,15 +683,18 @@ again: path->slots[0]--; extent_end = end; } + recow = 1; } - fi = btrfs_item_ptr(leaf, path->slots[0], - struct btrfs_file_extent_item); - other_start = end; other_end = 0; - if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino, - bytenr, &other_start, &other_end)) { + if (extent_mergeable(leaf, path->slots[0] + 1, + inode->i_ino, bytenr, orig_offset, + &other_start, &other_end)) { + if (recow) { + btrfs_release_path(root, path); + goto again; + } extent_end = other_end; del_slot = path->slots[0] + 1; del_nr++; @@ -650,8 +705,13 @@ again: } other_start = 0; other_end = start; - if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino, - bytenr, &other_start, &other_end)) { + if (extent_mergeable(leaf, path->slots[0] - 1, + inode->i_ino, bytenr, orig_offset, + &other_start, &other_end)) { + if (recow) { + btrfs_release_path(root, path); + goto again; + } key.offset = other_start; del_slot = path->slots[0]; del_nr++; @@ -660,22 +720,22 @@ again: inode->i_ino, orig_offset); BUG_ON(ret); } + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); if (del_nr == 0) { btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG); btrfs_mark_buffer_dirty(leaf); - goto out; - } - - fi = btrfs_item_ptr(leaf, del_slot - 1, - struct btrfs_file_extent_item); - btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG); - btrfs_set_file_extent_num_bytes(leaf, fi, - extent_end - key.offset); - btrfs_mark_buffer_dirty(leaf); + } else { + btrfs_set_file_extent_type(leaf, fi, + BTRFS_FILE_EXTENT_REG); + btrfs_set_file_extent_num_bytes(leaf, fi, + extent_end - key.offset); + btrfs_mark_buffer_dirty(leaf); - ret = btrfs_del_items(trans, root, path, del_slot, del_nr); - BUG_ON(ret); + ret = btrfs_del_items(trans, root, path, del_slot, del_nr); + BUG_ON(ret); + } out: btrfs_free_path(path); return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |