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Commit fc5da22a authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

tmpfs: fix off-by-one in max_blocks checks 



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: default avatarHugh Dickins <hughd@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d00ebeac

mm/shmem.c

+4 −2
Original line number Diff line number Diff line
@@ -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;