Commit 50122847 authored Jul 28, 2018 by Theodore Ts'o

ext4: fix check to prevent initializing reserved inodes



Commit 8844618d: "ext4: only look at the bg_flags field if it is
valid" will complain if block group zero does not have the
EXT4_BG_INODE_ZEROED flag set.  Unfortunately, this is not correct,
since a freshly created file system has this flag cleared.  It gets
almost immediately after the file system is mounted read-write --- but
the following somewhat unlikely sequence will end up triggering a
false positive report of a corrupted file system:

   mkfs.ext4 /dev/vdc
   mount -o ro /dev/vdc /vdc
   mount -o remount,rw /dev/vdc

Instead, when initializing the inode table for block group zero, test
to make sure that itable_unused count is not too large, since that is
the case that will result in some or all of the reserved inodes
getting cleared.

This fixes the failures reported by Eric Whiteney when running
generic/230 and generic/231 in the the nojournal test case.

Fixes: 8844618d ("ext4: only look at the bg_flags field if it is valid")
Reported-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent 8d5a803c

fs/ext4/ialloc.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1388,7 +1388,10 @@ int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
		ext4_itable_unused_count(sb, gdp)),
		sbi->s_inodes_per_block);

		if ((used_blks < 0) \|\| (used_blks > sbi->s_itb_per_group)) {
		if ((used_blks < 0) \|\| (used_blks > sbi->s_itb_per_group) \|\|
		((group == 0) && ((EXT4_INODES_PER_GROUP(sb) -
		ext4_itable_unused_count(sb, gdp)) <
		EXT4_FIRST_INO(sb)))) {
		ext4_error(sb, "Something is wrong with group %u: "
		"used itable blocks: %d; "
		"itable unused count: %u",

fs/ext4/super.c

+1 −7

Original line number	Diff line number	Diff line
		@@ -3141,14 +3141,8 @@ static ext4_group_t ext4_has_uninit_itable(struct super_block *sb)
		if (!gdp)
		continue;

		if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED))
		continue;
		if (group != 0)
		if (!(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED)))
		break;
		ext4_error(sb, "Inode table for bg 0 marked as "
		"needing zeroing");
		if (sb_rdonly(sb))
		return ngroups;
		}

		return group;

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