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[07/15] tmpfs: restore functionality of nr_inodes=0

Message ID 20200919042018.EijFHCeuD%akpm@linux-foundation.org
State New
Headers show
Series [01/15] mailmap: add older email addresses for Kees Cook | expand

Commit Message

Andrew Morton Sept. 19, 2020, 4:20 a.m. UTC
From: Byron Stanoszek <gandalf@winds.org>
Subject: tmpfs: restore functionality of nr_inodes=0

Commit e809d5f0b5c9 ("tmpfs: per-superblock i_ino support") made changes
to shmem_reserve_inode() in mm/shmem.c, however the original test for
(sbinfo->max_inodes) got dropped.  This causes mounting tmpfs with option
nr_inodes=0 to fail:

  # mount -ttmpfs -onr_inodes=0 none /ext0
  mount: /ext0: mount(2) system call failed: Cannot allocate memory.

This patch restores the nr_inodes=0 functionality.

Link: https://lkml.kernel.org/r/20200902035715.16414-1-gandalf@winds.org
Fixes: e809d5f0b5c9 ("tmpfs: per-superblock i_ino support")
Signed-off-by: Byron Stanoszek <gandalf@winds.org>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Chris Down <chris@chrisdown.name>	
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/shmem.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
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Patch

--- a/mm/shmem.c~tmpfs-restore-functionality-of-nr_inodes=0
+++ a/mm/shmem.c
@@ -279,11 +279,13 @@  static int shmem_reserve_inode(struct su
 
 	if (!(sb->s_flags & SB_KERNMOUNT)) {
 		spin_lock(&sbinfo->stat_lock);
-		if (!sbinfo->free_inodes) {
-			spin_unlock(&sbinfo->stat_lock);
-			return -ENOSPC;
+		if (sbinfo->max_inodes) {
+			if (!sbinfo->free_inodes) {
+				spin_unlock(&sbinfo->stat_lock);
+				return -ENOSPC;
+			}
+			sbinfo->free_inodes--;
 		}
-		sbinfo->free_inodes--;
 		if (inop) {
 			ino = sbinfo->next_ino++;
 			if (unlikely(is_zero_ino(ino)))