This is a note to let you know that I've just added the patch titled
ext4: fix reservation overflow in ext4_da_write_begin
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-fix-reservation-overflow-in-ext4_da_write_begin.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 0ff8947fc5f700172b37cbca811a38eb9cb81e08 Mon Sep 17 00:00:00 2001
From: Eric Sandeen <[email protected]>
Date: Sat, 11 Oct 2014 19:51:17 -0400
Subject: ext4: fix reservation overflow in ext4_da_write_begin
From: Eric Sandeen <[email protected]>
commit 0ff8947fc5f700172b37cbca811a38eb9cb81e08 upstream.
Delalloc write journal reservations only reserve 1 credit,
to update the inode if necessary. However, it may happen
once in a filesystem's lifetime that a file will cross
the 2G threshold, and require the LARGE_FILE feature to
be set in the superblock as well, if it was not set already.
This overruns the transaction reservation, and can be
demonstrated simply on any ext4 filesystem without the LARGE_FILE
feature already set:
dd if=/dev/zero of=testfile bs=1 seek=2147483646 count=1 \
conv=notrunc of=testfile
sync
dd if=/dev/zero of=testfile bs=1 seek=2147483647 count=1 \
conv=notrunc of=testfile
leads to:
EXT4-fs: ext4_do_update_inode:4296: aborting transaction: error 28 in
__ext4_handle_dirty_super
EXT4-fs error (device loop0) in ext4_do_update_inode:4301: error 28
EXT4-fs error (device loop0) in ext4_reserve_inode_write:4757: Readonly
filesystem
EXT4-fs error (device loop0) in ext4_dirty_inode:4876: error 28
EXT4-fs error (device loop0) in ext4_da_write_end:2685: error 28
Adjust the number of credits based on whether the flag is
already set, and whether the current write may extend past the
LARGE_FILE limit.
Signed-off-by: Eric Sandeen <[email protected]>
Signed-off-by: Theodore Ts'o <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/ext4/inode.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2514,6 +2514,20 @@ static int ext4_nonda_switch(struct supe
return 0;
}
+/* We always reserve for an inode update; the superblock could be there too */
+static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
+{
+ if (likely(EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+ EXT4_FEATURE_RO_COMPAT_LARGE_FILE)))
+ return 1;
+
+ if (pos + len <= 0x7fffffffULL)
+ return 1;
+
+ /* We might need to update the superblock to set LARGE_FILE */
+ return 2;
+}
+
static int ext4_da_write_begin(struct file *file, struct address_space
*mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
@@ -2564,7 +2578,8 @@ retry_grab:
* of file which has an already mapped buffer.
*/
retry_journal:
- handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, 1);
+ handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
+ ext4_da_write_credits(inode, pos, len));
if (IS_ERR(handle)) {
page_cache_release(page);
return PTR_ERR(handle);
Patches currently in stable-queue which might be from [email protected] are
queue-3.17/ext4-fix-reservation-overflow-in-ext4_da_write_begin.patch
queue-3.17/jbd2-free-bh-when-descriptor-block-checksum-fails.patch
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