lkml.org 
[lkml]   [2014]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.8 26/81] ext4: fix online resize with very large inode tables
Date
3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit b93c95353413041a8cebad915a8109619f66bcc6 upstream.

If a file system has a large number of inodes per block group, all of
the metadata blocks in a flex_bg may be larger than what can fit in a
single block group. Unfortunately, ext4_alloc_group_tables() in
resize.c was never tested to see if it would handle this case
correctly, and there were a large number of bugs which caused the
following sequence to result in a BUG_ON:

kernel bug at fs/ext4/resize.c:409!
...
call trace:
[<ffffffff81256768>] ext4_flex_group_add+0x1448/0x1830
[<ffffffff81257de2>] ext4_resize_fs+0x7b2/0xe80
[<ffffffff8123ac50>] ext4_ioctl+0xbf0/0xf00
[<ffffffff811c111d>] do_vfs_ioctl+0x2dd/0x4b0
[<ffffffff811b9df2>] ? final_putname+0x22/0x50
[<ffffffff811c1371>] sys_ioctl+0x81/0xa0
[<ffffffff81676aa9>] system_call_fastpath+0x16/0x1b
code: c8 4c 89 df e8 41 96 f8 ff 44 89 e8 49 01 c4 44 29 6d d4 0
rip [<ffffffff81254fa1>] set_flexbg_block_bitmap+0x171/0x180

This can be reproduced with the following command sequence:

mke2fs -t ext4 -i 4096 /dev/vdd 1G
mount -t ext4 /dev/vdd /vdd
resize2fs /dev/vdd 8G

To fix this, we need to make sure the right thing happens when a block
group's inode table straddles two block groups, which means the
following bugs had to be fixed:

1) Not clearing the BLOCK_UNINIT flag in the second block group in
ext4_alloc_group_tables --- the was proximate cause of the BUG_ON.

2) Incorrectly determining how many block groups contained contiguous
free blocks in ext4_alloc_group_tables().

3) Incorrectly setting the start of the next block range to be marked
in use after a discontinuity in setup_new_flex_group_blocks().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
fs/ext4/resize.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 28d5f2c..d2c12df 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -238,6 +238,7 @@ static int ext4_alloc_group_tables(struct super_block *sb,
ext4_group_t group;
ext4_group_t last_group;
unsigned overhead;
+ __u16 uninit_mask = (flexbg_size > 1) ? ~EXT4_BG_BLOCK_UNINIT : ~0;

BUG_ON(flex_gd->count == 0 || group_data == NULL);

@@ -261,7 +262,7 @@ next_group:
src_group++;
for (; src_group <= last_group; src_group++) {
overhead = ext4_group_overhead_blocks(sb, src_group);
- if (overhead != 0)
+ if (overhead == 0)
last_blk += group_data[src_group - group].blocks_count;
else
break;
@@ -275,8 +276,7 @@ next_group:
ext4_get_group_no_and_offset(sb, start_blk - 1, &group, NULL);
group -= group_data[0].group;
group_data[group].free_blocks_count--;
- if (flexbg_size > 1)
- flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
+ flex_gd->bg_flags[group] &= uninit_mask;
}

/* Allocate inode bitmaps */
@@ -287,22 +287,30 @@ next_group:
ext4_get_group_no_and_offset(sb, start_blk - 1, &group, NULL);
group -= group_data[0].group;
group_data[group].free_blocks_count--;
- if (flexbg_size > 1)
- flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
+ flex_gd->bg_flags[group] &= uninit_mask;
}

/* Allocate inode tables */
for (; it_index < flex_gd->count; it_index++) {
- if (start_blk + EXT4_SB(sb)->s_itb_per_group > last_blk)
+ unsigned int itb = EXT4_SB(sb)->s_itb_per_group;
+ ext4_fsblk_t next_group_start;
+
+ if (start_blk + itb > last_blk)
goto next_group;
group_data[it_index].inode_table = start_blk;
ext4_get_group_no_and_offset(sb, start_blk, &group, NULL);
+ next_group_start = ext4_group_first_block_no(sb, group + 1);
group -= group_data[0].group;
- group_data[group].free_blocks_count -=
- EXT4_SB(sb)->s_itb_per_group;
- if (flexbg_size > 1)
- flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;

+ if (start_blk + itb > next_group_start) {
+ flex_gd->bg_flags[group + 1] &= uninit_mask;
+ overhead = start_blk + itb - next_group_start;
+ group_data[group + 1].free_blocks_count -= overhead;
+ itb -= overhead;
+ }
+
+ group_data[group].free_blocks_count -= itb;
+ flex_gd->bg_flags[group] &= uninit_mask;
start_blk += EXT4_SB(sb)->s_itb_per_group;
}

@@ -615,7 +623,7 @@ handle_ib:
if (err)
goto out;
count = group_table_count[j];
- start = group_data[i].block_bitmap;
+ start = (&group_data[i].block_bitmap)[j];
block = start;
}

--
1.8.3.2


\
 
 \ /
  Last update: 2014-03-25 19:21    [W:0.559 / U:0.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site