On Saturday 1 August 2020 1:44:19 PM IST Chandan Babu R wrote: I messed up "git format-patch" command line and hence missed adding appropriate entries in TO and CC list for the patches themselves. I have resent the patches. I am sorry about the unnecessary noise. > 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 2035 [003] 9643.390490: probe:xfs_iflush_int: (ffffffffac6225c0) if_nextents=98511 inode=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_trans_resv_ext_cnt()) 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-v0. > > PS: I am planning to write the code which extends data/xattr extent > counters from 32-bit/16-bit to 64-bit/32-bit on top of these patches. > > fs/xfs/libxfs/xfs_attr.c | 33 ++++++++++-- > fs/xfs/libxfs/xfs_bmap.c | 7 +++ > fs/xfs/libxfs/xfs_trans_resv.c | 33 ++++++++++++ > fs/xfs/libxfs/xfs_trans_resv.h | 1 + > fs/xfs/xfs_bmap_item.c | 12 +++++ > fs/xfs/xfs_bmap_util.c | 40 ++++++++++++++ > fs/xfs/xfs_dquot.c | 7 ++- > fs/xfs/xfs_inode.c | 96 ++++++++++++++++++++++++++++++++++ > fs/xfs/xfs_iomap.c | 19 +++++++ > fs/xfs/xfs_reflink.c | 35 +++++++++++++ > fs/xfs/xfs_rtalloc.c | 4 ++ > fs/xfs/xfs_symlink.c | 18 +++++++ > 12 files changed, 301 insertions(+), 4 deletions(-) > > -- chandan
