jbd2: do not fail journal because of frozen_buffer allocation failure

Journal transaction might fail prematurely because the frozen_buffer
is allocated by GFP_NOFS request:
[   72.440013] do_get_write_access: OOM for frozen_buffer
[   72.440014] EXT4-fs: ext4_reserve_inode_write:4729: aborting transaction: Out of memory in __ext4_journal_get_write_access
[   72.440015] EXT4-fs error (device sda1) in ext4_reserve_inode_write:4735: Out of memory
(...snipped....)
[   72.495559] do_get_write_access: OOM for frozen_buffer
[   72.495560] EXT4-fs: ext4_reserve_inode_write:4729: aborting transaction: Out of memory in __ext4_journal_get_write_access
[   72.496839] do_get_write_access: OOM for frozen_buffer
[   72.496841] EXT4-fs: ext4_reserve_inode_write:4729: aborting transaction: Out of memory in __ext4_journal_get_write_access
[   72.505766] Aborting journal on device sda1-8.
[   72.505851] EXT4-fs (sda1): Remounting filesystem read-only

This wasn't a problem until "mm: page_alloc: do not lock up GFP_NOFS
allocations upon OOM" because small GPF_NOFS allocations never failed.
This allocation seems essential for the journal and GFP_NOFS is too
restrictive to the memory allocator so let's use __GFP_NOFAIL here to
emulate the previous behavior.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 081dff0..01e4652 100644 (file)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -966,14 +966,8 @@ repeat:
                if (!frozen_buffer) {
                        JBUFFER_TRACE(jh, "allocate memory for buffer");
                        jbd_unlock_bh_state(bh);
-                       frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
-                       if (!frozen_buffer) {
-                               printk(KERN_ERR "%s: OOM for frozen_buffer\n",
-                                      __func__);
-                               JBUFFER_TRACE(jh, "oom!");
-                               error = -ENOMEM;
-                               goto out;
-                       }
+                       frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
+                                                  GFP_NOFS | __GFP_NOFAIL);
                        goto repeat;
                }
                jh->b_frozen_data = frozen_buffer;
@@ -1226,15 +1220,9 @@ int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
                goto out;
 
 repeat:
-       if (!jh->b_committed_data) {
-               committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
-               if (!committed_data) {
-                       printk(KERN_ERR "%s: No memory for committed data\n",
-                               __func__);
-                       err = -ENOMEM;
-                       goto out;
-               }
-       }
+       if (!jh->b_committed_data)
+               committed_data = jbd2_alloc(jh2bh(jh)->b_size,
+                                           GFP_NOFS|__GFP_NOFAIL);
 
        jbd_lock_bh_state(bh);
        if (!jh->b_committed_data) {