From: Dave Chinner <dchinner@xxxxxxxxxx>
Because the counters use a custom batch size, the comparison
functions need to be aware of that batch size otherwise the
comparison does not work correctly. This leads to ASSERT failures
on generic/027 like this:
XFS: Assertion failed: 0, file: fs/xfs/xfs_mount.c, line: 1099
------------[ cut here ]------------
....
Call Trace:
[<ffffffff81522a39>] xfs_mod_icount+0x99/0xc0
[<ffffffff815285cb>] xfs_trans_unreserve_and_mod_sb+0x28b/0x5b0
[<ffffffff8152f941>] xfs_log_commit_cil+0x321/0x580
[<ffffffff81528e17>] xfs_trans_commit+0xb7/0x260
[<ffffffff81503d4d>] xfs_bmap_finish+0xcd/0x1b0
[<ffffffff8151da41>] xfs_inactive_ifree+0x1e1/0x250
[<ffffffff8151dbe0>] xfs_inactive+0x130/0x200
[<ffffffff81523a21>] xfs_fs_evict_inode+0x91/0xf0
[<ffffffff811f3958>] evict+0xb8/0x190
[<ffffffff811f433b>] iput+0x18b/0x1f0
[<ffffffff811e8853>] do_unlinkat+0x1f3/0x320
[<ffffffff811d548a>] ? filp_close+0x5a/0x80
[<ffffffff811e999b>] SyS_unlinkat+0x1b/0x40
[<ffffffff81e0892e>] system_call_fastpath+0x12/0x71
This is a regression introduced by commit 501ab32 ("xfs: use generic
percpu counters for inode counter").
This patch fixes the same problem for both the inode counter and the
free block counter in the superblocks.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
fs/xfs/xfs_mount.c | 34 ++++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 02f827f..461e791 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1100,14 +1100,18 @@ xfs_log_sbcount(xfs_mount_t *mp)
return xfs_sync_sb(mp, true);
}
+/*
+ * Deltas for the inode count are +/-64, hence we use a large batch size
+ * of 128 so we don't need to take the counter lock on every update.
+ */
+#define XFS_ICOUNT_BATCH 128
int
xfs_mod_icount(
struct xfs_mount *mp,
int64_t delta)
{
- /* deltas are +/-64, hence the large batch size of 128. */
- __percpu_counter_add(&mp->m_icount, delta, 128);
- if (percpu_counter_compare(&mp->m_icount, 0) < 0) {
+ __percpu_counter_add(&mp->m_icount, delta, XFS_ICOUNT_BATCH);
+ if (__percpu_counter_compare(&mp->m_icount, 0, XFS_ICOUNT_BATCH) < 0) {
ASSERT(0);
percpu_counter_add(&mp->m_icount, -delta);
return -EINVAL;
@@ -1129,6 +1133,14 @@ xfs_mod_ifree(
return 0;
}
+/*
+ * Deltas for the block count can vary from 1 to very large, but lock contention
+ * only occurs on frequent small block count updates such as in the delayed
+ * allocation path for buffered writes (page a time updates). Hence we set
+ * a large batch count (1024) to minimise global counter updates except when
+ * we get near to ENOSPC and we have to be very accurate with our updates.
+ */
+#define XFS_FDBLOCKS_BATCH 1024
int
xfs_mod_fdblocks(
struct xfs_mount *mp,
@@ -1167,25 +1179,19 @@ xfs_mod_fdblocks(
* Taking blocks away, need to be more accurate the closer we
* are to zero.
*
- * batch size is set to a maximum of 1024 blocks - if we are
- * allocating of freeing extents larger than this then we aren't
- * going to be hammering the counter lock so a lock per update
- * is not a problem.
- *
* If the counter has a value of less than 2 * max batch size,
* then make everything serialise as we are real close to
* ENOSPC.
*/
-#define __BATCH 1024
- if (percpu_counter_compare(&mp->m_fdblocks, 2 * __BATCH) < 0)
+ if (__percpu_counter_compare(&mp->m_fdblocks, 2 * XFS_FDBLOCKS_BATCH,
+ XFS_FDBLOCKS_BATCH) < 0)
batch = 1;
else
- batch = __BATCH;
-#undef __BATCH
+ batch = XFS_FDBLOCKS_BATCH;
__percpu_counter_add(&mp->m_fdblocks, delta, batch);
- if (percpu_counter_compare(&mp->m_fdblocks,
- XFS_ALLOC_SET_ASIDE(mp)) >= 0) {
+ if (__percpu_counter_compare(&mp->m_fdblocks, XFS_ALLOC_SET_ASIDE(mp),
+ XFS_FDBLOCKS_BATCH) >= 0) {
/* we had space! */
return 0;
}
--
2.0.0
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