This is a note to let you know that I've just added the patch titled
ext4: fix reference counting bug on block allocation error
to the 4.6-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-reference-counting-bug-on-block-allocation-error.patch
and it can be found in the queue-4.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 554a5ccc4e4a20c5f3ec859de0842db4b4b9c77e Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Date: Thu, 14 Jul 2016 23:02:47 -0400
Subject: ext4: fix reference counting bug on block allocation error
From: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
commit 554a5ccc4e4a20c5f3ec859de0842db4b4b9c77e upstream.
If we hit this error when mounted with errors=continue or
errors=remount-ro:
EXT4-fs error (device loop0): ext4_mb_mark_diskspace_used:2940: comm ext4.exe: Allocating blocks 5090-6081 which overlap fs metadata
then ext4_mb_new_blocks() will call ext4_mb_release_context() and try to
continue. However, ext4_mb_release_context() is the wrong thing to call
here since we are still actually using the allocation context.
Instead, just error out. We could retry the allocation, but there is a
possibility of getting stuck in an infinite loop instead, so this seems
safer.
[ Fixed up so we don't return EAGAIN to userspace. --tytso ]
Fixes: 8556e8f3b6 ("ext4: Don't allow new groups to be added during block allocation")
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 17 +++--------------
1 file changed, 3 insertions(+), 14 deletions(-)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2939,7 +2939,7 @@ ext4_mb_mark_diskspace_used(struct ext4_
ext4_error(sb, "Allocating blocks %llu-%llu which overlap "
"fs metadata", block, block+len);
/* File system mounted not to panic on error
- * Fix the bitmap and repeat the block allocation
+ * Fix the bitmap and return EFSCORRUPTED
* We leak some of the blocks here.
*/
ext4_lock_group(sb, ac->ac_b_ex.fe_group);
@@ -2948,7 +2948,7 @@ ext4_mb_mark_diskspace_used(struct ext4_
ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
if (!err)
- err = -EAGAIN;
+ err = -EFSCORRUPTED;
goto out_err;
}
@@ -4513,18 +4513,7 @@ repeat:
}
if (likely(ac->ac_status == AC_STATUS_FOUND)) {
*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);
- if (*errp == -EAGAIN) {
- /*
- * drop the reference that we took
- * in ext4_mb_use_best_found
- */
- ext4_mb_release_context(ac);
- ac->ac_b_ex.fe_group = 0;
- ac->ac_b_ex.fe_start = 0;
- ac->ac_b_ex.fe_len = 0;
- ac->ac_status = AC_STATUS_CONTINUE;
- goto repeat;
- } else if (*errp) {
+ if (*errp) {
ext4_discard_allocated_blocks(ac);
goto errout;
} else {
Patches currently in stable-queue which might be from vegard.nossum@xxxxxxxxxx are
queue-4.6/ext4-short-cut-orphan-cleanup-on-error.patch
queue-4.6/block-fix-use-after-free-in-seq-file.patch
queue-4.6/ext4-check-for-extents-that-wrap-around.patch
queue-4.6/net-irda-fix-null-pointer-dereference-on-memory-allocation-failure.patch
queue-4.6/ext4-validate-s_reserved_gdt_blocks-on-mount.patch
queue-4.6/ext4-don-t-call-ext4_should_journal_data-on-the-journal-inode.patch
queue-4.6/ext4-fix-reference-counting-bug-on-block-allocation-error.patch
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