XFS does not check for possible overflow of per-inode extent counter fields when adding extents to either data or attr fork. For e.g. 1. Insert 5 million xattrs (each having a value size of 255 bytes) and then delete 50% of them in an alternating manner. 2. On a 4k block sized XFS filesystem instance, the above causes 98511 extents to be created in the attr fork of the inode. xfsaild/loop0 2008 [003] 1475.127209: probe:xfs_inode_to_disk: (ffffffffa43fb6b0) if_nextents=98511 i_ino=131 3. The incore inode fork extent counter is a signed 32-bit quantity. However, the on-disk extent counter is an unsigned 16-bit quantity and hence cannot hold 98511 extents. 4. The following incorrect value is stored in the xattr extent counter, # xfs_db -f -c 'inode 131' -c 'print core.naextents' /dev/loop0 core.naextents = -32561 This patchset adds a new helper function (i.e. xfs_iext_count_may_overflow()) to check for overflow of the per-inode data and xattr extent counters and invokes it before starting an fs operation (e.g. creating a new directory entry). With this patchset applied, XFS detects counter overflows and returns with an error rather than causing a silent corruption. The patchset has been tested by executing xfstests with the following mkfs.xfs options, 1. -m crc=0 -b size=1k 2. -m crc=0 -b size=4k 3. -m crc=0 -b size=512 4. -m rmapbt=1,reflink=1 -b size=1k 5. -m rmapbt=1,reflink=1 -b size=4k The patches can also be obtained from https://github.com/chandanr/linux.git at branch xfs-reserve-extent-count-v3. Changelog: V2 -> V3: 1. Move the definition of xfs_iext_count_may_overflow() from libxfs/xfs_trans_resv.c to libxfs/xfs_inode_fork.c. Also, I tried to make xfs_iext_count_may_overflow() an inline function by placing the definition in libxfs/xfs_inode_fork.h. However this required that the definition of 'struct xfs_inode' be available, since xfs_iext_count_may_overflow() uses a 'struct xfs_inode *' type variable. 2. Handle XFS_COW_FORK within xfs_iext_count_may_overflow() by returning a success value. 3. Rename XFS_IEXT_ADD_CNT to XFS_IEXT_ADD_NOSPLIT_CNT. Thanks to Darrick for the suggesting the new name. 4. Expand comments to make use of 80 columns. V1 -> V2: 1. Rename helper function from xfs_trans_resv_ext_cnt() to xfs_iext_count_may_overflow(). 2. Define and use macros to represent fs operations and the corresponding increase in extent count. 3. Split the patches based on the fs operation being performed. Chandan Babu R (10): xfs: Add helper for checking per-inode extent count overflow xfs: Check for extent overflow when trivally adding a new extent xfs: Check for extent overflow when deleting an extent xfs: Check for extent overflow when adding/removing xattrs xfs: Check for extent overflow when adding/removing dir entries xfs: Check for extent overflow when writing to unwritten extent xfs: Check for extent overflow when inserting a hole xfs: Check for extent overflow when moving extent from cow to data fork xfs: Check for extent overflow when remapping an extent xfs: Check for extent overflow when swapping extents fs/xfs/libxfs/xfs_attr.c | 13 ++++++ fs/xfs/libxfs/xfs_bmap.c | 6 +++ fs/xfs/libxfs/xfs_inode_fork.c | 23 +++++++++++ fs/xfs/libxfs/xfs_inode_fork.h | 75 ++++++++++++++++++++++++++++++++++ fs/xfs/xfs_bmap_item.c | 4 ++ fs/xfs/xfs_bmap_util.c | 30 ++++++++++++++ fs/xfs/xfs_dquot.c | 8 +++- fs/xfs/xfs_inode.c | 27 ++++++++++++ fs/xfs/xfs_iomap.c | 10 +++++ fs/xfs/xfs_reflink.c | 10 +++++ fs/xfs/xfs_rtalloc.c | 5 +++ fs/xfs/xfs_symlink.c | 5 +++ 12 files changed, 215 insertions(+), 1 deletion(-) -- 2.28.0
