Log space reservation for xattr insert operation can be divided into two
parts,
1. Mount time
- Inode
- Superblock for accounting space allocations
- AGF for accounting space used by count, block number, rmap and refcnt
btrees.
2. The remaining log space can only be calculated at run time because,
- A local xattr can be large enough to cause a double split of the dabtree.
- The value of the xattr can be large enough to be stored in remote
blocks. The contents of the remote blocks are not logged.
The log space reservation could be,
- 2 * XFS_DA_NODE_MAXDEPTH number of blocks. Additional XFS_DA_NODE_MAXDEPTH
number of blocks are required if xattr is large enough to cause another
split of the dabtree path from root to leaf block.
- BMBT blocks for storing (2 * XFS_DA_NODE_MAXDEPTH) record
entries. Additional XFS_DA_NODE_MAXDEPTH number of blocks are required in
case of a double split of the dabtree path from root to leaf blocks.
- Space for logging blocks of count, block number, rmap and refcnt btrees.
At present mount time log reservation includes block count required for a
single split of the dabtree. The dabtree block count is also taken into
account by xfs_attr_calc_size().
Also, AGF log space reservation isn't accounted for.
Due to the reasons mentioned above, log reservation calculation for xattr
insert operation gives an incorrect value.
Apart from the above, xfs_log_calc_max_attrsetm_res() passes byte count as
an argument to XFS_NEXTENTADD_SPACE_RES() instead of block count.
This patchset aims to fix this log space reservation calcuation bug.
Patches 1-2 and 4-6 refactor the existing code around
xfs_attr_calc_size(). Patches 3 and 7 change the logic to fix log
reservation calculation.
The patchset can also be obtained from
https://github.com/chandanr/linux/tree/xfs-fix-attr-resv-calc-v4.
Changelog:
V1 -> V2:
1. Use convenience variables to reduce indentation of code.
V2 -> V3:
1. Introduce 'struct xfs_attr_set_resv' to collect various block size
reservations when inserting an xattr.
2. Add xfs_calc_attr_res() to calculate the total log reservation to
required when inserting an xattr.
V3 -> V4:
1. Rebase the patchset on top of Christoph's "Clean attr interface"
patchset.
2. Split the patchset into
- Patches which refactor the existing calculation in
xfs_attr_calc_size().
- One patch which fixes the calculation inside
xfs_attr_calc_size().
3. Fix indentation issues.
4. Pass attribute geometry pointer to xfs_attr_leaf_newentsize()
instead of a pointer to 'struct xfs_mount'.
Chandan Rajendra (7):
xfs: Pass xattr name and value length explicitly to
xfs_attr_leaf_newentsize
xfs: xfs_attr_calc_size: Use local variables to track individual space
components
xfs: xfs_attr_calc_size: Calculate Bmbt blks only once
xfs: Introduce struct xfs_attr_set_resv
xfs: xfs_attr_calc_size: Explicitly pass mp, namelen and valuelen args
xfs: Make xfs_attr_calc_size() non-static
xfs: Fix log reservation calculation for xattr insert operation
fs/xfs/libxfs/xfs_attr.c | 107 ++++++++++++++++++---------------
fs/xfs/libxfs/xfs_attr.h | 18 ++++++
fs/xfs/libxfs/xfs_attr_leaf.c | 39 ++++++++----
fs/xfs/libxfs/xfs_attr_leaf.h | 3 +-
fs/xfs/libxfs/xfs_log_rlimit.c | 16 ++---
fs/xfs/libxfs/xfs_trans_resv.c | 50 ++++++++-------
fs/xfs/libxfs/xfs_trans_resv.h | 2 +
7 files changed, 140 insertions(+), 95 deletions(-)
--
2.19.1
