ext2 relies on ->write_inode being called from sync_inode_metadata in
fsync in order to sync the inode. However I_DIRTY_SYNC gets cleared
after a call to this guy, and it doesn't actually write back and wait
on the inode block unless it is called for sync. This means that write_inode
from background writeback can kill the inode dirty bits without the data
getting to disk. Fsync will subsequently miss it.
The fix is for ->write_inode to dirty the buffers/cache, and then ->fsync to
write back the dirty data. In the full filesystem sync case, buffercache
writeback in the generic code will write back the dirty data. Other
filesystems could use ->sync_fs for this.
Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>
---
This is the other side of the inode-metadata-writeback fuckup coin (I
suspect many other filesystems also have problems here, but I've only
dared to look at a couple as yet).
Index: linux-2.6/fs/ext2/inode.c
===================================================================
--- linux-2.6.orig/fs/ext2/inode.c 2010-11-22 23:20:44.000000000 +1100
+++ linux-2.6/fs/ext2/inode.c 2010-11-22 23:38:26.000000000 +1100
@@ -1505,16 +1505,8 @@ static int __ext2_write_inode(struct ino
} else for (n = 0; n < EXT2_N_BLOCKS; n++)
raw_inode->i_block[n] = ei->i_data[n];
mark_buffer_dirty(bh);
- if (do_sync) {
- sync_dirty_buffer(bh);
- if (buffer_req(bh) && !buffer_uptodate(bh)) {
- printk ("IO error syncing ext2 inode [%s:%08lx]\n",
- sb->s_id, (unsigned long) ino);
- err = -EIO;
- }
- }
- ei->i_state &= ~EXT2_STATE_NEW;
brelse (bh);
+ ei->i_state &= ~EXT2_STATE_NEW;
return err;
}
Index: linux-2.6/fs/ext2/file.c
===================================================================
--- linux-2.6.orig/fs/ext2/file.c 2010-11-22 23:35:24.000000000 +1100
+++ linux-2.6/fs/ext2/file.c 2010-11-22 23:38:34.000000000 +1100
@@ -45,14 +45,30 @@ int ext2_fsync(struct file *file, int da
int ret;
struct super_block *sb = file->f_mapping->host->i_sb;
struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
+ ino_t ino = inode->i_ino;
+ struct buffer_head *bh;
+ struct ext2_inode *raw_inode;
ret = generic_file_fsync(file, datasync);
if (ret == -EIO || test_and_clear_bit(AS_EIO, &mapping->flags)) {
/* We don't really know where the IO error happened... */
ext2_error(sb, __func__,
"detected IO error when writing metadata buffers");
+ return -EIO;
+ }
+
+ raw_inode = ext2_get_inode(sb, ino, &bh);
+ if (IS_ERR(raw_inode))
+ return -EIO;
+
+ sync_dirty_buffer(bh);
+ if (buffer_req(bh) && !buffer_uptodate(bh)) {
+ printk ("IO error syncing ext2 inode [%s:%08lx]\n",
+ sb->s_id, (unsigned long) ino);
ret = -EIO;
}
+ brelse (bh);
+
return ret;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
