| From 554a5ccc4e4a20c5f3ec859de0842db4b4b9c77e Mon Sep 17 00:00:00 2001 |
| From: Vegard Nossum <vegard.nossum@oracle.com> |
| Date: Thu, 14 Jul 2016 23:02:47 -0400 |
| Subject: ext4: fix reference counting bug on block allocation error |
| |
| From: Vegard Nossum <vegard.nossum@oracle.com> |
| |
| 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@oracle.com> |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/mballoc.c | 17 +++-------------- |
| 1 file changed, 3 insertions(+), 14 deletions(-) |
| |
| --- a/fs/ext4/mballoc.c |
| +++ b/fs/ext4/mballoc.c |
| @@ -2932,7 +2932,7 @@ 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); |
| @@ -2941,7 +2941,7 @@ 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; |
| } |
| |
| @@ -4506,18 +4506,7 @@ 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 { |