Re: [PATCH] ext4: Add statx support

From: Andreas Dilger
Date: Fri Mar 31 2017 - 17:07:18 EST


On Mar 31, 2017, at 9:28 AM, David Howells <dhowells@xxxxxxxxxx> wrote:
>
> Return enhanced file attributes from the Ext4 filesystem. This includes
> the following:
>
> (1) The inode creation time (i_crtime) as stx_btime, setting STATX_BTIME.
>
> (2) Certain FS_xxx_FL flags are mapped to stx_attribute flags.
>
> This requires that all ext4 inodes have a getattr call, not just some of
> them, so to this end, split the ext4_getattr() function and only call part
> of it where appropriate.
>
> Example output:
>
> [root@andromeda ~]# touch foo
> [root@andromeda ~]# chattr +ai foo
> [root@andromeda ~]# /tmp/test-statx foo
> statx(foo) = 0
> results=fff
> Size: 0 Blocks: 0 IO Block: 4096 regular file
> Device: 08:12 Inode: 2101950 Links: 1
> Access: (0644/-rw-r--r--) Uid: 0 Gid: 0
> Access: 2016-02-11 17:08:29.031795451+0000
> Modify: 2016-02-11 17:08:29.031795451+0000
> Change: 2016-02-11 17:11:11.987790114+0000
> Birth: 2016-02-11 17:08:29.031795451+0000
> Attributes: 0000000000000030 (-------- -------- -------- -------- -------- -------- -------- --ai----)
>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>

Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>

One minor nit below, but the current patch is OK.

> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 4247d8d25687..5d02b922afa3 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -5390,11 +5390,40 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
> int ext4_getattr(const struct path *path, struct kstat *stat,
> u32 request_mask, unsigned int query_flags)
> {
> - struct inode *inode;
> - unsigned long long delalloc_blocks;
> + struct inode *inode = d_inode(path->dentry);
> + struct ext4_inode *raw_inode;
> + struct ext4_inode_info *ei = EXT4_I(inode);
> + unsigned int flags;
> +
> + if (EXT4_FITS_IN_INODE(raw_inode, ei, i_crtime)) {
> + stat->result_mask |= STATX_BTIME;
> + stat->btime.tv_sec = ei->i_crtime.tv_sec;
> + stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
> + }
> +
> + flags = ei->i_flags & EXT4_FL_USER_VISIBLE;

Strictly speaking, since the relevant flags are being checked individually,
there is no value to masking with EXT4_FL_USER_VISIBLE. That is only
required if you are returning the whole "flags" value directly.

Cheers, Andreas

> + if (flags & EXT4_APPEND_FL)
> + stat->attributes |= STATX_ATTR_APPEND;
> + if (flags & EXT4_COMPR_FL)
> + stat->attributes |= STATX_ATTR_COMPRESSED;
> + if (flags & EXT4_ENCRYPT_FL)
> + stat->attributes |= STATX_ATTR_ENCRYPTED;
> + if (flags & EXT4_IMMUTABLE_FL)
> + stat->attributes |= STATX_ATTR_IMMUTABLE;
> + if (flags & EXT4_NODUMP_FL)
> + stat->attributes |= STATX_ATTR_NODUMP;
>
> - inode = d_inode(path->dentry);
> generic_fillattr(inode, stat);
> + return 0;
> +}
> +
> +int ext4_file_getattr(const struct path *path, struct kstat *stat,
> + u32 request_mask, unsigned int query_flags)
> +{
> + struct inode *inode = d_inode(path->dentry);
> + u64 delalloc_blocks;
> +
> + ext4_getattr(path, stat, request_mask, query_flags);
>
> /*
> * If there is inline data in the inode, the inode will normally not





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