74 lines
2.9 KiB
Diff
74 lines
2.9 KiB
Diff
From b0dd6b70f0fda17ae9762fbb72d98e40a4f66556 Mon Sep 17 00:00:00 2001
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From: Theodore Ts'o <tytso@mit.edu>
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Date: Thu, 7 Jun 2012 18:56:06 -0400
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Subject: ext4: fix the free blocks calculation for ext3 file systems w/ uninit_bg
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From: Theodore Ts'o <tytso@mit.edu>
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commit b0dd6b70f0fda17ae9762fbb72d98e40a4f66556 upstream.
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Ext3 filesystems that are converted to use as many ext4 file system
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features as possible will enable uninit_bg to speed up e2fsck times.
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These file systems will have a native ext3 layout of inode tables and
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block allocation bitmaps (as opposed to ext4's flex_bg layout).
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Unfortunately, in these cases, when first allocating a block in an
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uninitialized block group, ext4 would incorrectly calculate the number
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of free blocks in that block group, and then errorneously report that
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the file system was corrupt:
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EXT4-fs error (device vdd): ext4_mb_generate_buddy:741: group 30, 32254 clusters in bitmap, 32258 in gd
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This problem can be reproduced via:
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mke2fs -q -t ext4 -O ^flex_bg /dev/vdd 5g
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mount -t ext4 /dev/vdd /mnt
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fallocate -l 4600m /mnt/test
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The problem was caused by a bone headed mistake in the check to see if a
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particular metadata block was part of the block group.
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Many thanks to Kees Cook for finding and bisecting the buggy commit
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which introduced this bug (commit fd034a84e1, present since v3.2).
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Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
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Reported-by: Kees Cook <keescook@chromium.org>
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Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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Tested-by: Kees Cook <keescook@chromium.org>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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fs/ext4/balloc.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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--- a/fs/ext4/balloc.c
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+++ b/fs/ext4/balloc.c
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@@ -90,8 +90,8 @@ unsigned ext4_num_overhead_clusters(stru
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* unusual file system layouts.
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*/
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if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
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- block_cluster = EXT4_B2C(sbi, (start -
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- ext4_block_bitmap(sb, gdp)));
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+ block_cluster = EXT4_B2C(sbi,
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+ ext4_block_bitmap(sb, gdp) - start);
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if (block_cluster < num_clusters)
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block_cluster = -1;
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else if (block_cluster == num_clusters) {
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@@ -102,7 +102,7 @@ unsigned ext4_num_overhead_clusters(stru
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if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
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inode_cluster = EXT4_B2C(sbi,
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- start - ext4_inode_bitmap(sb, gdp));
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+ ext4_inode_bitmap(sb, gdp) - start);
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if (inode_cluster < num_clusters)
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inode_cluster = -1;
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else if (inode_cluster == num_clusters) {
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@@ -114,7 +114,7 @@ unsigned ext4_num_overhead_clusters(stru
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itbl_blk = ext4_inode_table(sb, gdp);
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for (i = 0; i < sbi->s_itb_per_group; i++) {
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if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
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- c = EXT4_B2C(sbi, start - itbl_blk + i);
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+ c = EXT4_B2C(sbi, itbl_blk + i - start);
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if ((c < num_clusters) || (c == inode_cluster) ||
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(c == block_cluster) || (c == itbl_cluster))
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continue;
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