[PATCH V4 7/7] xfs: Fix log reservation calculation for xattr insert operation

Chandan Rajendra
2020-02-23T07:29:01Z

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.

Presently, 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.

To fix these issues, this commit changes xfs_attr_calc_size() to also
calculate the number of dabtree blocks that need to be logged.

xfs_attr_set() uses the following values computed by xfs_attr_calc_size()
1. The number of dabtree blocks that need to be logged.
2. The number of remote blocks that need to be allocated.
3. The number of dabtree blocks that need to be allocated.
4. The number of bmbt blocks that need to be allocated.
5. The total number of blocks that need to be allocated.

... to compute number of bytes that need to be reserved in the log.

This commit also modifies xfs_log_calc_max_attrsetm_res() to invoke
xfs_attr_calc_size() to obtain the number of blocks to be logged which it uses
to figure out the total number of bytes to be logged.

Signed-off-by: Chandan Rajendra <chandanrlinux@gmail.com>
---
libxfs/xfs_attr.c | 6 ++---
libxfs/xfs_attr.h | 3 +++
libxfs/xfs_log_rlimit.c | 16 ++++++-------
libxfs/xfs_trans_resv.c | 50 ++++++++++++++++++++---------------------
libxfs/xfs_trans_resv.h | 2 ++
5 files changed, 40 insertions(+), 37 deletions(-)

diff --git a/libxfs/xfs_attr.c b/libxfs/xfs_attr.c
index 343ae79f..144d7268 100644
--- a/libxfs/xfs_attr.c
+++ b/libxfs/xfs_attr.c
@@ -182,9 +182,11 @@ xfs_attr_calc_size(
size = xfs_attr_leaf_newentsize(mp->m_attr_geo, namelen, valuelen,
local);
resv->total_dablks = XFS_DAENTER_BLOCKS(mp, XFS_ATTR_FORK);
+ resv->log_dablks = 2 * resv->total_dablks;
if (*local) {
if (size > (blksize / 2)) {
/* Double split possible */
+ resv->log_dablks += resv->total_dablks;
resv->total_dablks *= 2;
}
resv->rmt_blks = 0;
@@ -349,9 +351,7 @@ xfs_attr_set(
return error;
}

- tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
- M_RES(mp)->tr_attrsetrt.tr_logres *
- args->total;
+ tres.tr_logres = xfs_calc_attr_res(mp, &resv);
tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
total = args->total;
diff --git a/libxfs/xfs_attr.h b/libxfs/xfs_attr.h
index 0e387230..83508148 100644
--- a/libxfs/xfs_attr.h
+++ b/libxfs/xfs_attr.h
@@ -74,6 +74,9 @@ struct xfs_attr_list_context {
};

struct xfs_attr_set_resv {
+ /* Number of blocks in the da btree that we might need to log. */
+ unsigned int log_dablks;
+
/* Number of unlogged blocks needed to store the remote attr value. */
unsigned int rmt_blks;

diff --git a/libxfs/xfs_log_rlimit.c b/libxfs/xfs_log_rlimit.c
index c8398b7d..b14d06c3 100644
--- a/libxfs/xfs_log_rlimit.c
+++ b/libxfs/xfs_log_rlimit.c
@@ -10,6 +10,7 @@
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
+#include "xfs_attr.h"
#include "xfs_da_format.h"
#include "xfs_trans_space.h"
#include "xfs_da_btree.h"
@@ -21,19 +22,18 @@
*/
STATIC int
xfs_log_calc_max_attrsetm_res(
- struct xfs_mount *mp)
+ struct xfs_mount *mp)
{
- int size;
- int nblks;
+ struct xfs_attr_set_resv resv;
+ int size;
+ int local;

size = xfs_attr_leaf_entsize_local_max(mp->m_attr_geo->blksize) -
MAXNAMELEN - 1;
- nblks = XFS_DAENTER_SPACE_RES(mp, XFS_ATTR_FORK);
- nblks += XFS_B_TO_FSB(mp, size);
- nblks += XFS_NEXTENTADD_SPACE_RES(mp, size, XFS_ATTR_FORK);
+ xfs_attr_calc_size(mp, &resv, size, 0, &local);
+ ASSERT(local == 1);

- return M_RES(mp)->tr_attrsetm.tr_logres +
- M_RES(mp)->tr_attrsetrt.tr_logres * nblks;
+ return xfs_calc_attr_res(mp, &resv);
}

/*
diff --git a/libxfs/xfs_trans_resv.c b/libxfs/xfs_trans_resv.c
index f0b48a7d..5eaa680e 100644
--- a/libxfs/xfs_trans_resv.c
+++ b/libxfs/xfs_trans_resv.c
@@ -16,6 +16,7 @@
#include "xfs_bmap_btree.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
+#include "xfs_attr.h"
#include "xfs_quota_defs.h"

#define _ALLOC true
@@ -699,12 +700,10 @@ xfs_calc_attrinval_reservation(
* Setting an attribute at mount time.
* the inode getting the attribute
* the superblock for allocations
- * the agfs extents are allocated from
- * the attribute btree * max depth
- * the inode allocation btree
+ * the agf extents are allocated from
* Since attribute transaction space is dependent on the size of the attribute,
* the calculation is done partially at mount time and partially at runtime(see
- * below).
+ * xfs_attr_calc_size()).
*/
STATIC uint
xfs_calc_attrsetm_reservation(
@@ -712,27 +711,7 @@ xfs_calc_attrsetm_reservation(
{
return XFS_DQUOT_LOGRES(mp) +
xfs_calc_inode_res(mp, 1) +
- xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) +
- xfs_calc_buf_res(XFS_DA_NODE_MAXDEPTH, XFS_FSB_TO_B(mp, 1));
-}
-
-/*
- * Setting an attribute at runtime, transaction space unit per block.
- * the superblock for allocations: sector size
- * the inode bmap btree could join or split: max depth * block size
- * Since the runtime attribute transaction space is dependent on the total
- * blocks needed for the 1st bmap, here we calculate out the space unit for
- * one block so that the caller could figure out the total space according
- * to the attibute extent length in blocks by:
- * ext * M_RES(mp)->tr_attrsetrt.tr_logres
- */
-STATIC uint
-xfs_calc_attrsetrt_reservation(
- struct xfs_mount *mp)
-{
- return xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) +
- xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_ATTR_FORK),
- XFS_FSB_TO_B(mp, 1));
+ xfs_calc_buf_res(2, mp->m_sb.sb_sectsize);
}

/*
@@ -830,6 +809,25 @@ xfs_calc_sb_reservation(
return xfs_calc_buf_res(1, mp->m_sb.sb_sectsize);
}

+uint
+xfs_calc_attr_res(
+ struct xfs_mount *mp,
+ struct xfs_attr_set_resv *resv)
+{
+ unsigned int space_blks;
+ unsigned int attr_res;
+
+ space_blks = xfs_allocfree_log_count(mp,
+ resv->total_dablks + resv->bmbt_blks);
+
+ attr_res = M_RES(mp)->tr_attrsetm.tr_logres +
+ xfs_calc_buf_res(resv->log_dablks, mp->m_attr_geo->blksize) +
+ xfs_calc_buf_res(resv->bmbt_blks, mp->m_sb.sb_blocksize) +
+ xfs_calc_buf_res(space_blks, mp->m_sb.sb_blocksize);
+
+ return attr_res;
+}
+
void
xfs_trans_resv_calc(
struct xfs_mount *mp,
@@ -940,7 +938,7 @@ xfs_trans_resv_calc(
resp->tr_ichange.tr_logres = xfs_calc_ichange_reservation(mp);
resp->tr_fsyncts.tr_logres = xfs_calc_swrite_reservation(mp);
resp->tr_writeid.tr_logres = xfs_calc_writeid_reservation(mp);
- resp->tr_attrsetrt.tr_logres = xfs_calc_attrsetrt_reservation(mp);
+ resp->tr_attrsetrt.tr_logres = 0;
resp->tr_clearagi.tr_logres = xfs_calc_clear_agi_bucket_reservation(mp);
resp->tr_growrtzero.tr_logres = xfs_calc_growrtzero_reservation(mp);
resp->tr_growrtfree.tr_logres = xfs_calc_growrtfree_reservation(mp);
diff --git a/libxfs/xfs_trans_resv.h b/libxfs/xfs_trans_resv.h
index 7241ab28..3a6a0bf2 100644
--- a/libxfs/xfs_trans_resv.h
+++ b/libxfs/xfs_trans_resv.h
@@ -7,6 +7,7 @@
#define __XFS_TRANS_RESV_H__

struct xfs_mount;
+struct xfs_attr_set_resv;

/*
* structure for maintaining pre-calculated transaction reservations.
@@ -91,6 +92,7 @@ struct xfs_trans_resv {
#define XFS_ATTRSET_LOG_COUNT 3
#define XFS_ATTRRM_LOG_COUNT 3

+uint xfs_calc_attr_res(struct xfs_mount *mp, struct xfs_attr_set_resv *resv);
void xfs_trans_resv_calc(struct xfs_mount *mp, struct xfs_trans_resv *resp);
uint xfs_allocfree_log_count(struct xfs_mount *mp, uint num_ops);

--
2.19.1