* [PATCH 0/2] Bail out if transaction can cause extent count to overflow
@ 2020-08-01 8:14 Chandan Babu R
2020-08-01 8:31 ` Chandan Babu R
0 siblings, 1 reply; 2+ messages in thread
From: Chandan Babu R @ 2020-08-01 8:14 UTC (permalink / raw)
To: linux-xfs; +Cc: Chandan Babu R, darrick.wong, david
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(-)
--
2.27.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH 0/2] Bail out if transaction can cause extent count to overflow
2020-08-01 8:14 [PATCH 0/2] Bail out if transaction can cause extent count to overflow Chandan Babu R
@ 2020-08-01 8:31 ` Chandan Babu R
0 siblings, 0 replies; 2+ messages in thread
From: Chandan Babu R @ 2020-08-01 8:31 UTC (permalink / raw)
To: linux-xfs; +Cc: darrick.wong, david
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
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