ext4: fix reference counting bug on block allocation error (554a5ccc) · Commits · 戴 / test

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: ("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> Cc: stable@vger.kernel.org

fs/ext4/mballoc.c

+3 −14

Original line number	Diff line number	Diff line
		@@ -2943,7 +2943,7 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
		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);
		@@ -2952,7 +2952,7 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
		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;
		}

		@@ -4517,18 +4517,7 @@ 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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