3.16.83-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Qu Wenruo wqu@suse.com
commit 69fc6cbbac542c349b3d350d10f6e394c253c81d upstream.
[BUG] If we run btrfs with CONFIG_BTRFS_FS_RUN_SANITY_TESTS=y, it will instantly cause kernel panic like:
------ ... assertion failed: 0, file: fs/btrfs/disk-io.c, line: 3853 ... Call Trace: btrfs_mark_buffer_dirty+0x187/0x1f0 [btrfs] setup_items_for_insert+0x385/0x650 [btrfs] __btrfs_drop_extents+0x129a/0x1870 [btrfs] ... -----
[Cause] Btrfs will call btrfs_check_leaf() in btrfs_mark_buffer_dirty() to check if the leaf is valid with CONFIG_BTRFS_FS_RUN_SANITY_TESTS=y.
However quite some btrfs_mark_buffer_dirty() callers(*) don't really initialize its item data but only initialize its item pointers, leaving item data uninitialized.
This makes tree-checker catch uninitialized data as error, causing such panic.
*: These callers include but not limited to setup_items_for_insert() btrfs_split_item() btrfs_expand_item()
[Fix] Add a new parameter @check_item_data to btrfs_check_leaf(). With @check_item_data set to false, item data check will be skipped and fallback to old btrfs_check_leaf() behavior.
So we can still get early warning if we screw up item pointers, and avoid false panic.
Cc: Filipe Manana fdmanana@gmail.com Reported-by: Lakshmipathi.G lakshmipathi.g@gmail.com Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: Liu Bo bo.li.liu@oracle.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com [bwh: Backported to 4.4: adjust context] Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/btrfs/disk-io.c | 10 ++++++++-- fs/btrfs/tree-checker.c | 27 ++++++++++++++++++++++----- fs/btrfs/tree-checker.h | 14 +++++++++++++- 3 files changed, 43 insertions(+), 8 deletions(-)
--- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -575,7 +575,7 @@ static int btree_readpage_end_io_hook(st * that we don't try and read the other copies of this block, just * return -EIO. */ - if (found_level == 0 && btrfs_check_leaf(root, eb)) { + if (found_level == 0 && btrfs_check_leaf_full(root, eb)) { set_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags); ret = -EIO; } @@ -3702,7 +3702,13 @@ void btrfs_mark_buffer_dirty(struct exte buf->len, root->fs_info->dirty_metadata_batch); #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY - if (btrfs_header_level(buf) == 0 && btrfs_check_leaf(root, buf)) { + /* + * Since btrfs_mark_buffer_dirty() can be called with item pointer set + * but item data not updated. + * So here we should only check item pointers, not item data. + */ + if (btrfs_header_level(buf) == 0 && + btrfs_check_leaf_relaxed(root, buf)) { btrfs_print_leaf(root, buf); ASSERT(0); } --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -195,7 +195,8 @@ static int check_leaf_item(struct btrfs_ return ret; }
-int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf) +static int check_leaf(struct btrfs_root *root, struct extent_buffer *leaf, + bool check_item_data) { struct btrfs_fs_info *fs_info = root->fs_info; /* No valid key type is 0, so all key should be larger than this key */ @@ -299,10 +300,15 @@ int btrfs_check_leaf(struct btrfs_root * return -EUCLEAN; }
- /* Check if the item size and content meet other criteria */ - ret = check_leaf_item(root, leaf, &key, slot); - if (ret < 0) - return ret; + if (check_item_data) { + /* + * Check if the item size and content meet other + * criteria + */ + ret = check_leaf_item(root, leaf, &key, slot); + if (ret < 0) + return ret; + }
prev_key.objectid = key.objectid; prev_key.type = key.type; @@ -312,6 +318,17 @@ int btrfs_check_leaf(struct btrfs_root * return 0; }
+int btrfs_check_leaf_full(struct btrfs_root *root, struct extent_buffer *leaf) +{ + return check_leaf(root, leaf, true); +} + +int btrfs_check_leaf_relaxed(struct btrfs_root *root, + struct extent_buffer *leaf) +{ + return check_leaf(root, leaf, false); +} + int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node) { unsigned long nr = btrfs_header_nritems(node); --- a/fs/btrfs/tree-checker.h +++ b/fs/btrfs/tree-checker.h @@ -20,7 +20,19 @@ #include "ctree.h" #include "extent_io.h"
-int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf); +/* + * Comprehensive leaf checker. + * Will check not only the item pointers, but also every possible member + * in item data. + */ +int btrfs_check_leaf_full(struct btrfs_root *root, struct extent_buffer *leaf); + +/* + * Less strict leaf checker. + * Will only check item pointers, not reading item data. + */ +int btrfs_check_leaf_relaxed(struct btrfs_root *root, + struct extent_buffer *leaf); int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node);
#endif