On Wed, Nov 08, 2017 at 08:54:24AM +0800, Qu Wenruo wrote: > [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. >
Reviewed-by: Liu Bo <bo.li....@oracle.com> Thanks, -liubo > Cc: Filipe Manana <fdman...@gmail.com> > Reported-by: Lakshmipathi.G <lakshmipath...@gmail.com> > Signed-off-by: Qu Wenruo <w...@suse.com> > --- > 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(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index efce9a2fa9be..10a2a579cc7f 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -610,7 +610,7 @@ static int btree_readpage_end_io_hook(struct btrfs_io_bio > *io_bio, > * 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; > } > @@ -3848,7 +3848,13 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf) > buf->len, > 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(buf); > ASSERT(0); > } > diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c > index 114fc5f0ecc5..ce4ed6ec8f39 100644 > --- a/fs/btrfs/tree-checker.c > +++ b/fs/btrfs/tree-checker.c > @@ -242,7 +242,8 @@ static int check_leaf_item(struct btrfs_root *root, > 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 */ > @@ -361,10 +362,15 @@ int btrfs_check_leaf(struct btrfs_root *root, struct > extent_buffer *leaf) > 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; > @@ -374,6 +380,17 @@ int btrfs_check_leaf(struct btrfs_root *root, struct > extent_buffer *leaf) > 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); > diff --git a/fs/btrfs/tree-checker.h b/fs/btrfs/tree-checker.h > index 96c486e95d70..3d53e8d6fda0 100644 > --- 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 > -- > 2.15.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html