From: Chandan Babu R <chandanrlinux@gmail.com>
To: linux-xfs@vger.kernel.org
Cc: Chandan Babu R <chandanrlinux@gmail.com>,
darrick.wong@oracle.com, david@fromorbit.com
Subject: [PATCH 0/2] Bail out if transaction can cause extent count to overflow
Date: Sat, 1 Aug 2020 13:44:19 +0530 [thread overview]
Message-ID: <20200801081421.10798-1-chandanrlinux@gmail.com> (raw)
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
next reply other threads:[~2020-08-01 8:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-01 8:14 Chandan Babu R [this message]
2020-08-01 8:31 ` [PATCH 0/2] Bail out if transaction can cause extent count to overflow Chandan Babu R
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200801081421.10798-1-chandanrlinux@gmail.com \
--to=chandanrlinux@gmail.com \
--cc=darrick.wong@oracle.com \
--cc=david@fromorbit.com \
--cc=linux-xfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).