Re: [PATCH 3/4] ext4: Add iomap support for inline data

Jan Kara
2017-08-30T12:47:27Z

On Tue 29-08-17 16:29:41, Andreas Gruenbacher wrote:
> Report inline data as an IOMAP_F_DATA_INLINE mapping. This allows to
> switch to iomap_seek_hole and iomap_seek_data in ext4_llseek, and will
> make switching to iomap_fiemap in ext4_fiemap easier as well.
>
> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Just one nit and one comment below. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

> ---
> fs/ext4/ext4.h | 4 ++++
> fs/ext4/inline.c | 33 +++++++++++++++++++++++++++++++++
> fs/ext4/inode.c | 10 ++++++++--
> 3 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index a2bb7d2870e4..017e55942a49 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -3048,6 +3048,10 @@ extern struct buffer_head *ext4_get_first_inline_block(struct inode *inode,
> extern int ext4_inline_data_fiemap(struct inode *inode,
> struct fiemap_extent_info *fieinfo,
> int *has_inline, __u64 start, __u64 len);
> +
> +struct iomap;
> +extern int ext4_inline_data_iomap(struct inode *inode, struct iomap *iomap);
> +
> extern int ext4_try_to_evict_inline_data(handle_t *handle,
> struct inode *inode,
> int needed);
> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
> index 28c5c3abddb3..21a078fef80f 100644
> --- a/fs/ext4/inline.c
> +++ b/fs/ext4/inline.c
> @@ -12,6 +12,7 @@
> * GNU General Public License for more details.
> */
>
> +#include <linux/iomap.h>
> #include <linux/fiemap.h>
>
> #include "ext4_jbd2.h"
> @@ -1827,6 +1828,38 @@ int ext4_destroy_inline_data(handle_t *handle, struct inode *inode)
> return ret;
> }
>
> +int ext4_inline_data_iomap(struct inode *inode, struct iomap *iomap)
> +{
> + __u64 addr;
> + int error = -ENOENT;
> + struct ext4_iloc iloc;
> +
> + down_read(&EXT4_I(inode)->xattr_sem);
> + if (!ext4_has_inline_data(inode))
> + goto out;

Hum, ENOENT looks rather arbitrary for a lost race with inode conversion.
Maybe EAGAIN would be better? We use it in some other place as well to
indicate that inode has been converted...

> +
> + error = ext4_get_inode_loc(inode, &iloc);
> + if (error)
> + goto out;

Using ext4_get_inode_loc() just to get block + offset of the inode is a bit
overkill since it will also allocate buffer_head, load the block with inode
from disk, etc. But since this is not performance critical and the buffer
is likely to be in cache anyway, I can live with this I guess.

Honza

--
Jan Kara <jack@suse.com>
SUSE Labs, CR