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Subject[PATCH] Ext3 online resizing locking issue
This simple patch provides a fix for a locking issue found in the online
resizing code. The problem actually happened while trying to resize the
filesystem trough the resize=xxx option in a remount.

Signed-off-by: Glauber de Oliveira Costa <gocosta@br.ibm.com>


diff -up linux-2.6.13-rc6-orig/fs/ext3/ioctl.c linux/fs/ext3/ioctl.c
--- linux-2.6.13-rc6-orig/fs/ext3/ioctl.c 2005-08-24 17:48:22.000000000 -0300
+++ linux/fs/ext3/ioctl.c 2005-08-24 15:12:48.000000000 -0300
@@ -206,7 +206,9 @@ flags_err:
if (get_user(n_blocks_count, (__u32 __user *)arg))
return -EFAULT;

+ lock_super(sb);
err = ext3_group_extend(sb, EXT3_SB(sb)->s_es, n_blocks_count);
+ unlock_super(sb);
journal_lock_updates(EXT3_SB(sb)->s_journal);
journal_flush(EXT3_SB(sb)->s_journal);
journal_unlock_updates(EXT3_SB(sb)->s_journal);
Only in linux/fs/ext3: patch-mnt_resize
diff -up linux-2.6.13-rc6-orig/fs/ext3/resize.c linux/fs/ext3/resize.c
--- linux-2.6.13-rc6-orig/fs/ext3/resize.c 2005-08-24 17:48:22.000000000 -0300
+++ linux/fs/ext3/resize.c 2005-08-24 15:15:28.000000000 -0300
@@ -884,7 +884,9 @@ exit_put:
/* Extend the filesystem to the new number of blocks specified. This entry
* point is only used to extend the current filesystem to the end of the last
* existing group. It can be accessed via ioctl, or by "remount,resize=<size>"
- * for emergencies (because it has no dependencies on reserved blocks).
+ * for emergencies (because it has no dependencies on reserved blocks).
+ *
+ * It should be called with sb->s_lock held
*
* If we _really_ wanted, we could use default values to call ext3_group_add()
* allow the "remount" trick to work for arbitrary resizing, assuming enough
@@ -959,7 +961,6 @@ int ext3_group_extend(struct super_block
goto exit_put;
}

- lock_super(sb);
if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) {
ext3_warning(sb, __FUNCTION__,
"multiple resizers run on filesystem!\n");
@@ -978,7 +979,6 @@ int ext3_group_extend(struct super_block
es->s_blocks_count = cpu_to_le32(o_blocks_count + add);
ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
sb->s_dirt = 1;
- unlock_super(sb);
ext3_debug("freeing blocks %ld through %ld\n", o_blocks_count,
o_blocks_count + add);
ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
diff -up linux-2.6.13-rc6-orig/fs/ext3/super.c linux/fs/ext3/super.c
--- linux-2.6.13-rc6-orig/fs/ext3/super.c 2005-08-24 17:48:22.000000000 -0300
+++ linux/fs/ext3/super.c 2005-08-24 15:13:16.000000000 -0300
@@ -639,8 +639,8 @@ static match_table_t tokens = {
{Opt_quota, "quota"},
{Opt_quota, "usrquota"},
{Opt_barrier, "barrier=%u"},
+ {Opt_resize, "resize=%u"},
{Opt_err, NULL},
- {Opt_resize, "resize"},
};

static unsigned long get_sb_block(void **data)
-
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