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Date: Sun, 14 Aug 2016 22:07:57 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Vegard Nossum <vegard.nossum@...cle.com>, Theodore Tso <tytso@....edu>, "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> Subject: [PATCH 3.14 29/29] ext4: fix reference counting bug on block allocation error 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vegard Nossum <vegard.nossum@...cle.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@...cle.com> Signed-off-by: Theodore Ts'o <tytso@....edu> Cc: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/ext4/mballoc.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2897,7 +2897,7 @@ 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 EUCLEAN * We leak some of the blocks here. */ ext4_lock_group(sb, ac->ac_b_ex.fe_group); @@ -2906,7 +2906,7 @@ 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 = -EUCLEAN; goto out_err; } @@ -4476,18 +4476,7 @@ 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 {
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