Re: [PATCH 6/9] xfs: Add xfs_has_attr and subroutines

Brian Foster
2019-04-22T13:00:53Z

On Fri, Apr 12, 2019 at 03:50:33PM -0700, Allison Henderson wrote:
> This patch adds a new functions to check for the existence of
> an attribute. Subroutines are also added to handle the cases
> of leaf blocks, nodes or shortform. We will need this later
> for delayed attributes since delayed operations cannot return
> error codes.
>
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
> fs/xfs/libxfs/xfs_attr.c | 78 +++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/libxfs/xfs_attr.h | 1 +
> fs/xfs/libxfs/xfs_attr_leaf.c | 33 ++++++++++++++++++
> fs/xfs/libxfs/xfs_attr_leaf.h | 1 +
> 4 files changed, 113 insertions(+)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index c3477fa7..0042708 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -53,6 +53,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
> STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
> STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args, bool roll_trans);
> STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args, bool roll_trans);
> +STATIC int xfs_leaf_has_attr(xfs_da_args_t *args);
>
> /*
> * Internal routines when attribute list is more than one block.
> @@ -60,6 +61,7 @@ STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args, bool roll_trans);
> STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> STATIC int xfs_attr_node_addname(xfs_da_args_t *args, bool roll_trans);
> STATIC int xfs_attr_node_removename(xfs_da_args_t *args, bool roll_trans);
> +STATIC int xfs_attr_node_hasname(xfs_da_args_t *args);
> STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
> STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
>
> @@ -301,6 +303,29 @@ xfs_attr_set_args(
> }
>
> /*
> + * Return successful if attr is found, or ENOATTR if not
> + */
> +int
> +xfs_has_attr(
> + struct xfs_da_args *args)
> +{
> + struct xfs_inode *dp = args->dp;
> + int error;
> +
> + if (!xfs_inode_hasattr(dp))
> + error = -ENOATTR;
> + else if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL) {
> + ASSERT(dp->i_afp->if_flags & XFS_IFINLINE);
> + error = xfs_shortform_has_attr(args);
> + } else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
> + error = xfs_leaf_has_attr(args);
> + else
> + error = xfs_attr_node_hasname(args);

I think it's usually expected to keep the {} braces around each branch
of a multi-branch if/else when at least one branch has multiple lines.

Also, I see that at least some of this code is pulled from existing
xattr functions. For example, the xfs_shortform_has_attr() code
currently exists in xfs_attr_shortform_remove(),
xfs_attr_shortform_add(), etc. Similar for xfs_leaf_has_attr() and
xfs_attr_leaf_removename(), etc.

Rather than just adding new, not yet used functions, can we turn this
patch more into a refactor where these new functions are reused by
existing code where applicable? That reduces duplication and also
facilitates review.

Brian

> +
> + return error;
> +}
> +
> +/*
> * Remove the attribute specified in @args.
> */
> int
> @@ -836,6 +861,29 @@ xfs_attr_leaf_addname(
> }
>
> /*
> + * Return successful if attr is found, or ENOATTR if not
> + */
> +STATIC int
> +xfs_leaf_has_attr(
> + struct xfs_da_args *args)
> +{
> + struct xfs_buf *bp;
> + int error = 0;
> +
> + args->blkno = 0;
> + error = xfs_attr3_leaf_read(args->trans, args->dp,
> + args->blkno, -1, &bp);
> + if (error)
> + return error;
> +
> + error = xfs_attr3_leaf_lookup_int(bp, args);
> + error = (error == -ENOATTR) ? -ENOATTR : 0;
> + xfs_trans_brelse(args->trans, bp);
> +
> + return error;
> +}
> +
> +/*
> * Remove a name from the leaf attribute list structure
> *
> * This leaf block cannot have a "remote" value, we only call this routine
> @@ -1166,6 +1214,36 @@ xfs_attr_node_addname(
> }
>
> /*
> + * Return successful if attr is found, or ENOATTR if not
> + */
> +STATIC int
> +xfs_attr_node_hasname(
> + struct xfs_da_args *args)
> +{
> + struct xfs_da_state *state;
> + struct xfs_inode *dp;
> + int retval, error;
> +
> + /*
> + * Tie a string around our finger to remind us where we are.
> + */
> + dp = args->dp;
> + state = xfs_da_state_alloc();
> + state->args = args;
> + state->mp = dp->i_mount;
> +
> + /*
> + * Search to see if name exists, and get back a pointer to it.
> + */
> + error = xfs_da3_node_lookup_int(state, &retval);
> + if (error || (retval != -EEXIST)) {
> + if (error == 0)
> + error = retval;
> + }
> + return error;
> +}
> +
> +/*
> * Remove a name from a B-tree attribute list.
> *
> * This will involve walking down the Btree, and may involve joining
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 83b3621..974c963 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -168,6 +168,7 @@ int xfs_attr_set_args(struct xfs_da_args *args, struct xfs_buf **leaf_bp,
> bool roll_trans);
> int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name,
> size_t namelen, int flags);
> +int xfs_has_attr(struct xfs_da_args *args);
> int xfs_attr_remove_args(struct xfs_da_args *args, bool roll_trans);
> int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
> int flags, struct attrlist_cursor_kern *cursor);
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index 128bfe9..e9f2f53 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -622,6 +622,39 @@ xfs_attr_fork_remove(
> }
>
> /*
> + * Return successful if attr is found, or ENOATTR if not
> + */
> +int
> +xfs_shortform_has_attr(
> + struct xfs_da_args *args)
> +{
> + struct xfs_attr_shortform *sf;
> + struct xfs_attr_sf_entry *sfe;
> + int base = sizeof(struct xfs_attr_sf_hdr);
> + int size = 0;
> + int end;
> + int i;
> +
> + sf = (struct xfs_attr_shortform *)args->dp->i_afp->if_u1.if_data;
> + sfe = &sf->list[0];
> + end = sf->hdr.count;
> + for (i = 0; i < end; sfe = XFS_ATTR_SF_NEXTENTRY(sfe),
> + base += size, i++) {
> + size = XFS_ATTR_SF_ENTSIZE(sfe);
> + if (sfe->namelen != args->namelen)
> + continue;
> + if (memcmp(sfe->nameval, args->name, args->namelen) != 0)
> + continue;
> + if (!xfs_attr_namesp_match(args->flags, sfe->flags))
> + continue;
> + break;
> + }
> + if (i == end)
> + return -ENOATTR;
> + return 0;
> +}
> +
> +/*
> * Remove an attribute from the shortform attribute list structure.
> */
> int
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
> index 9d830ec..98dd169 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.h
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
> @@ -39,6 +39,7 @@ int xfs_attr_shortform_getvalue(struct xfs_da_args *args);
> int xfs_attr_shortform_to_leaf(struct xfs_da_args *args,
> struct xfs_buf **leaf_bp);
> int xfs_attr_shortform_remove(struct xfs_da_args *args);
> +int xfs_shortform_has_attr(struct xfs_da_args *args);
> int xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
> int xfs_attr_shortform_bytesfit(struct xfs_inode *dp, int bytes);
> xfs_failaddr_t xfs_attr_shortform_verify(struct xfs_inode *ip);
> --
> 2.7.4
>