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tmpfs: fix off-by-one in max_blocks checks

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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>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2011-04-14 15:22:07 -07:00 committed by Linus Torvalds
parent d00ebeac5f
commit fc5da22ae3
1 changed files with 4 additions and 2 deletions
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6
mm/shmem.c
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@ -421,7 +421,8 @@ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long
* 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);
@ -1397,7 +1398,8 @@ 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;