From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH] tmpfs: fix off-by-one in max_blocks checks
Date: Sat, 19 Mar 2011 22:33:05 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1103192230480.1659@sister.anvils> (raw)
If you fill up a tmpfs, df was showing
tmpfs 460800 - - - /tmp
because of an off-by-one in the max_blocks checks. Fix it so df shows
tmpfs 460800 460800 0 100% /tmp
Signed-off-by: Hugh Dickins <hughd@google.com>
---
mm/shmem.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- 2.6.38/mm/shmem.c 2011-03-14 18:20:32.000000000 -0700
+++ linux/mm/shmem.c 2011-03-19 22:02:17.000000000 -0700
@@ -422,7 +422,8 @@ static swp_entry_t *shmem_swp_alloc(stru
* a waste to allocate index if we cannot allocate data.
*/
if (sbinfo->max_blocks) {
- if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0)
+ if (percpu_counter_compare(&sbinfo->used_blocks,
+ sbinfo->max_blocks - 1) >= 0)
return ERR_PTR(-ENOSPC);
percpu_counter_inc(&sbinfo->used_blocks);
spin_lock(&inode->i_lock);
@@ -1399,7 +1400,8 @@ repeat:
shmem_swp_unmap(entry);
sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks) {
- if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) ||
+ if (percpu_counter_compare(&sbinfo->used_blocks,
+ sbinfo->max_blocks) >= 0 ||
shmem_acct_block(info->flags)) {
spin_unlock(&info->lock);
error = -ENOSPC;
--
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reply other threads:[~2011-03-20 5:33 UTC|newest]
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