ext4: lock block groups when initializing

I noticed when filling a 1T filesystem with 4 threads using the
fs_mark benchmark:

fs_mark -d /mnt/test -D 256 -n 100000 -t 4 -s 20480 -F -S 0

that I occasionally got checksum mismatch errors:

EXT4-fs error (device sdb): ext4_init_inode_bitmap: Checksum bad for group 6935

etc.  I'd reliably get 4-5 of them during the run.

It appears that the problem is likely a race to init the bg's
when the uninit_bg feature is enabled.

With the patch below, which adds sb_bgl_locking around initialization,
I was able to complete several runs with no errors or warnings.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 386cb79..1ae5004 100644 (file)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -321,12 +321,15 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
        if (bh_uptodate_or_lock(bh))
                return bh;
 
+       spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
        if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                ext4_init_block_bitmap(sb, bh, block_group, desc);
                set_buffer_uptodate(bh);
                unlock_buffer(bh);
+               spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
                return bh;
        }
+       spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
        if (bh_submit_read(bh) < 0) {
                put_bh(bh);
                ext4_error(sb, __func__,

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 09cdcd5..655e760 100644 (file)
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -118,12 +118,15 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
        if (bh_uptodate_or_lock(bh))
                return bh;
 
+       spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
        if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
                ext4_init_inode_bitmap(sb, bh, block_group, desc);
                set_buffer_uptodate(bh);
                unlock_buffer(bh);
+               spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
                return bh;
        }
+       spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
        if (bh_submit_read(bh) < 0) {
                put_bh(bh);
                ext4_error(sb, __func__,
@@ -735,7 +738,7 @@ got:
 
                        /* When marking the block group with
                         * ~EXT4_BG_INODE_UNINIT we don't want to depend
-                        * on the value of bg_itable_unsed even though
+                        * on the value of bg_itable_unused even though
                         * mke2fs could have initialized the same for us.
                         * Instead we calculated the value below
                         */

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 8d141a2..4258d32 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -787,13 +787,16 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
                if (bh_uptodate_or_lock(bh[i]))
                        continue;
 
+               spin_lock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
                if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                        ext4_init_block_bitmap(sb, bh[i],
                                                first_group + i, desc);
                        set_buffer_uptodate(bh[i]);
                        unlock_buffer(bh[i]);
+                       spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
                        continue;
                }
+               spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
                get_bh(bh[i]);
                bh[i]->b_end_io = end_buffer_read_sync;
                submit_bh(READ, bh[i]);

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 876e1c6..511997e 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1621,6 +1621,7 @@ static int ext4_check_descriptors(struct super_block *sb)
                               "(block %llu)!", i, inode_table);
                        return 0;
                }
+               spin_lock(sb_bgl_lock(sbi, i));
                if (!ext4_group_desc_csum_verify(sbi, i, gdp)) {
                        printk(KERN_ERR "EXT4-fs: ext4_check_descriptors: "
                               "Checksum for group %lu failed (%u!=%u)\n",
@@ -1629,6 +1630,7 @@ static int ext4_check_descriptors(struct super_block *sb)
                        if (!(sb->s_flags & MS_RDONLY))
                                return 0;
                }
+               spin_unlock(sb_bgl_lock(sbi, i));
                if (!flexbg_flag)
                        first_block += EXT4_BLOCKS_PER_GROUP(sb);
        }