On Apr 3, 2024, at 1:22 AM, Sweet Tea Dorminy <[email protected]> 
wrote:
> 
> Signed-off-by: Sweet Tea Dorminy <[email protected]>
> ---
> fs/nilfs2/inode.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
> index 4d3c347c982b..e3108f2cead7 100644
> --- a/fs/nilfs2/inode.c
> +++ b/fs/nilfs2/inode.c
> @@ -1160,7 +1160,7 @@ int nilfs_fiemap(struct inode *inode, struct 
> fiemap_extent_info *fieinfo,
> {
>       struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
>       __u64 logical = 0, phys = 0, size = 0;
> -     __u32 flags = 0;
> +     __u32 flags = FIEMAP_EXTENT_HAS_PHYS_LEN;
> 
>       loff_t isize;
>       sector_t blkoff, end_blkoff;
>       sector_t delalloc_blkoff;
> @@ -1197,7 +1197,9 @@ int nilfs_fiemap(struct inode *inode, struct 
> fiemap_extent_info *fieinfo,
>                       if (blkoff > end_blkoff)
>                               break;
> 
> -                     flags = FIEMAP_EXTENT_MERGED | FIEMAP_EXTENT_DELALLOC;
> +                     flags = FIEMAP_EXTENT_MERGED |
> +                             FIEMAP_EXTENT_DELALLOC |
> +                             FIEMAP_EXTENT_HAS_PHYS_LEN;

IMHO, rather than setting "flags = FIEMAP..." here, it would be better to
initialize "flags |= FIEMAP_HAS_PHYS_LEN" right after fiemap_fill_next_extent()
is called, and use "flags |= FIEMAP_EXTENT_MERGED | FIEMAP_EXTENT_DELALLOC" 
here.

That makes it more clear that MERGED|DELALLOC are "add-on" flags beyond the
base flags, and if more flags are added in the future (e.g. COMPRESSED) then
the flag management will be simpler (more on this below).

> @@ -1261,14 +1263,16 @@ int nilfs_fiemap(struct inode *inode, struct 
> fiemap_extent_info *fieinfo,
>                                               break;
> 
>                                       /* Start another extent */
> -                                     flags = FIEMAP_EXTENT_MERGED;
> +                                     flags = FIEMAP_EXTENT_MERGED |
> +                                             FIEMAP_EXTENT_HAS_PHYS_LEN;

Strictly speaking, this new extent should not have FIEMAP_EXTENT_MERGED set,
and start out with only FIEMAP_EXTENT_HAS_PHYS_LEN, since it has not actually
been merged with anything.

>                                       logical = blkoff << blkbits;
>                                       phys = blkphy << blkbits;
>                                       size = n << blkbits;
>                               }
>                       } else {
>                               /* Start a new extent */
> -                             flags = FIEMAP_EXTENT_MERGED;
> +                             flags = FIEMAP_EXTENT_MERGED |
> +                                     FIEMAP_EXTENT_HAS_PHYS_LEN;

Then this should be "flags |= FIEMAP_EXTENT_MERGED" only once a second
block has been merged into the prior one.

Cheers, Andreas





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