From b93c95353413041a8cebad915a8109619f66bcc6 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 15 Feb 2014 21:33:13 -0500 Subject: [PATCH] ext4: fix online resize with very large inode tables 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: [] ext4_flex_group_add+0x1448/0x1830 [] ext4_resize_fs+0x7b2/0xe80 [] ext4_ioctl+0xbf0/0xf00 [] do_vfs_ioctl+0x2dd/0x4b0 [] ? final_putname+0x22/0x50 [] sys_ioctl+0x81/0xa0 [] 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 [] 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" Cc: stable@vger.kernel.org --- fs/ext4/resize.c | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index c5adbb318a90..69a62610a6ca 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -243,6 +243,7 @@ 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); @@ -266,7 +267,7 @@ 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; @@ -280,8 +281,7 @@ next_group: group = ext4_get_group_number(sb, start_blk - 1); 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 */ @@ -292,22 +292,30 @@ next_group: group = ext4_get_group_number(sb, start_blk - 1); 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; - group = ext4_get_group_number(sb, start_blk - 1); + group = ext4_get_group_number(sb, start_blk); + 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; } @@ -620,7 +628,7 @@ 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; } -- 2.20.1