On Mon 18-04-22 14:37:35, Zhang Yi wrote:
> Symlink's external data block is one kind of metadata block, and now
> that almost all ext4 metadata block's page cache (e.g. directory blocks,
> quota blocks...) belongs to bdev backing inode except the symlink. It
> is essentially worked in data=journal mode like other regular file's
> data block because probably in order to make it simple for generic VFS
> code handling symlinks or some other historical reasons, but the logic
> of creating external data block in ext4_symlink() is complicated. and it
> also make things confused if user do not want to let the filesystem
> worked in data=journal mode. This patch convert the final exceptional
> case and make things clean, move the mapping of the symlink's external
> data block to bdev like any other metadata block does.
>
> Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
The patch looks good now except for one problem:
> +static const char *ext4_get_link(struct dentry *dentry, struct inode *inode,
> + struct delayed_call *callback)
> +{
> + struct buffer_head *bh;
> +
> + if (!dentry) {
> + bh = ext4_getblk(NULL, inode, 0, 0);
This is problematic because in RCU walk mode we must not sleep and
ext4_getblk() may sleep in ext4_map_blocks(). So we'd need some trick to
avoid that.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
