ext4 crypto: don't let data integrity writebacks fail with ENOMEM
We don't want the writeback triggered from the journal commit (in
data=writeback mode) to cause the journal to abort due to
generic_writepages() returning an ENOMEM error. In addition, if
fsync() fails with ENOMEM, most applications will probably not do the
right thing.
So if we are doing a data integrity sync, and ext4_encrypt() returns
ENOMEM, we will submit any queued I/O to date, and then retry the
allocation using GFP_NOFAIL.
Google-Bug-Id: 27641567
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index d77d15f..51b3492 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -23,6 +23,7 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
+#include <linux/backing-dev.h>
#include "ext4_jbd2.h"
#include "xattr.h"
@@ -470,9 +471,20 @@
if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
nr_to_submit) {
- data_page = ext4_encrypt(inode, page);
+ gfp_t gfp_flags = GFP_NOFS;
+
+ retry_encrypt:
+ data_page = ext4_encrypt(inode, page, gfp_flags);
if (IS_ERR(data_page)) {
ret = PTR_ERR(data_page);
+ if (ret == ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
+ if (io->io_bio) {
+ ext4_io_submit(io);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
+ }
+ gfp_flags |= __GFP_NOFAIL;
+ goto retry_encrypt;
+ }
data_page = NULL;
goto out;
}