Re: [PATCH v7 03/19] xfs: Add xfs_has_attr and subroutines

Brian Foster
2020-02-24T13:08:13Z

On Sat, Feb 22, 2020 at 07:05:55PM -0700, Allison Collins wrote:
> From: Allison Henderson <allison.henderson@oracle.com>
>
> 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.
> Common code that appears in existing attr add and remove functions have been
> factored out to help reduce the appearance of duplicated code. We will need these
> routines later for delayed attributes since delayed operations cannot return error
> codes.
>
> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
> ---
> fs/xfs/libxfs/xfs_attr.c | 171 ++++++++++++++++++++++++++++--------------
> fs/xfs/libxfs/xfs_attr.h | 1 +
> fs/xfs/libxfs/xfs_attr_leaf.c | 111 +++++++++++++++++----------
> fs/xfs/libxfs/xfs_attr_leaf.h | 3 +
> 4 files changed, 188 insertions(+), 98 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 9acdb23..2255060 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
...
> @@ -310,6 +313,37 @@ xfs_attr_set_args(
> }
>
> /*
> + * Return EEXIST if attr is found, or ENOATTR if not
> + */
> +int
> +xfs_has_attr(
> + struct xfs_da_args *args)
> +{
> + struct xfs_inode *dp = args->dp;
> + struct xfs_buf *bp = NULL;
> + int error;
> +
> + if (!xfs_inode_hasattr(dp))
> + return -ENOATTR;
> +
> + if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL) {
> + ASSERT(dp->i_afp->if_flags & XFS_IFINLINE);
> + return xfs_attr_sf_findname(args, NULL, NULL);

Nit: any reason we use "findname" here and "hasname" for the other two
variants?

Just a few other nit level things..

> + }
> +
> + if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> + error = xfs_attr_leaf_hasname(args, &bp);
> +
> + if (bp)
> + xfs_trans_brelse(args->trans, bp);
> +
> + return error;
> + }
> +
> + return xfs_attr_node_hasname(args, NULL);
> +}
> +
> +/*
> * Remove the attribute specified in @args.
> */
> int
...
> @@ -773,12 +822,11 @@ xfs_attr_leaf_removename(
> * Remove the attribute.
> */
> dp = args->dp;
> - args->blkno = 0;
> - error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, &bp);
> - if (error)
> +
> + error = xfs_attr_leaf_hasname(args, &bp);
> + if (error != -ENOATTR && error != -EEXIST)
> return error;
>
> - error = xfs_attr3_leaf_lookup_int(bp, args);
> if (error == -ENOATTR) {

It looks like some of these error checks could be cleaned up where the
helper function is used. I.e., something like the following here:

if (error == -ENOATTR) {
xfs_trans_brelse(...);
return error;
} else if (error != -EEXIST)
return error;

> xfs_trans_brelse(args->trans, bp);
> return error;
> @@ -817,12 +865,10 @@ xfs_attr_leaf_get(xfs_da_args_t *args)
>
> trace_xfs_attr_leaf_get(args);
>
> - args->blkno = 0;
> - error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, &bp);
> - if (error)
> + error = xfs_attr_leaf_hasname(args, &bp);
> + if (error != -ENOATTR && error != -EEXIST)
> return error;
>
> - error = xfs_attr3_leaf_lookup_int(bp, args);
> if (error != -EEXIST) {
> xfs_trans_brelse(args->trans, bp);
> return error;

Similar thing here, just reordering the checks simplifies the logic.

> @@ -832,6 +878,41 @@ xfs_attr_leaf_get(xfs_da_args_t *args)
> return error;
> }
>
> +/*
> + * Return EEXIST if attr is found, or ENOATTR if not
> + * statep: If not null is set to point at the found state. Caller will
> + * be responsible for freeing the state in this case.
> + */
> +STATIC int
> +xfs_attr_node_hasname(
> + struct xfs_da_args *args,
> + struct xfs_da_state **statep)
> +{
> + struct xfs_da_state *state;
> + int retval, error;
> +
> + state = xfs_da_state_alloc();
> + state->args = args;
> + state->mp = args->dp->i_mount;
> +
> + if (statep != NULL)
> + *statep = NULL;
> +
> + /*
> + * Search to see if name exists, and get back a pointer to it.
> + */
> + error = xfs_da3_node_lookup_int(state, &retval);
> + if (error == 0) {
> + if (statep != NULL)
> + *statep = state;
> + return retval;
> + }
> +
> + xfs_da_state_free(state);
> +
> + return error;
> +}
> +
> /*========================================================================
> * External routines when attribute list size > geo->blksize
> *========================================================================*/
...
> @@ -1316,31 +1381,23 @@ xfs_attr_node_get(xfs_da_args_t *args)
> {
> xfs_da_state_t *state;
> xfs_da_state_blk_t *blk;
> - int error, retval;
> + int error;
> int i;
>
> trace_xfs_attr_node_get(args);
>
> - state = xfs_da_state_alloc();
> - state->args = args;
> - state->mp = args->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 = error;
> - goto out_release;
> - }
> - if (retval != -EEXIST)
> + error = xfs_attr_node_hasname(args, &state);
> + if (error != -EEXIST)
> goto out_release;
>
> /*
> * Get the value, local or "remote"
> */
> blk = &state->path.blk[state->path.active - 1];
> - retval = xfs_attr3_leaf_getvalue(blk->bp, args);
> + error = xfs_attr3_leaf_getvalue(blk->bp, args);
>
> /*
> * If not in a transaction, we have to release all the buffers.
> @@ -1352,7 +1409,7 @@ xfs_attr_node_get(xfs_da_args_t *args)
> }
>
> xfs_da_state_free(state);

Do we need an 'if (state)' check here like the other node funcs?

> - return retval;
> + return error;
> }
>
> /* Returns true if the attribute entry name is valid. */
...
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index cb5ef66..9d6b68c 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -654,18 +654,66 @@ xfs_attr_shortform_create(xfs_da_args_t *args)
> }
>
> /*
> + * Return -EEXIST if attr is found, or -ENOATTR if not
> + * args: args containing attribute name and namelen
> + * sfep: If not null, pointer will be set to the last attr entry found on
> + -EEXIST. On -ENOATTR pointer is left at the last entry in the list
> + * basep: If not null, pointer is set to the byte offset of the entry in the
> + * list on -EEXIST. On -ENOATTR, pointer is left at the byte offset of
> + * the last entry in the list
> + */
> +int
> +xfs_attr_sf_findname(
> + struct xfs_da_args *args,
> + struct xfs_attr_sf_entry **sfep,
> + unsigned int *basep)
> +{
> + struct xfs_attr_shortform *sf;
> + struct xfs_attr_sf_entry *sfe;
> + unsigned 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++) {

Slightly more readable to align indendation with the sfe assignment
above.

Brian

> + size = XFS_ATTR_SF_ENTSIZE(sfe);
> + if (sfe->namelen != args->name.len)
> + continue;
> + if (memcmp(sfe->nameval, args->name.name, args->name.len) != 0)
> + continue;
> + if (!xfs_attr_namesp_match(args->name.type, sfe->flags))
> + continue;
> + break;
> + }
> +
> + if (sfep != NULL)
> + *sfep = sfe;
> +
> + if (basep != NULL)
> + *basep = base;
> +
> + if (i == end)
> + return -ENOATTR;
> + return -EEXIST;
> +}
> +
> +/*
> * Add a name/value pair to the shortform attribute list.
> * Overflow from the inode has already been checked for.
> */
> void
> -xfs_attr_shortform_add(xfs_da_args_t *args, int forkoff)
> +xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff)
> {
> - xfs_attr_shortform_t *sf;
> - xfs_attr_sf_entry_t *sfe;
> - int i, offset, size;
> - xfs_mount_t *mp;
> - xfs_inode_t *dp;
> - struct xfs_ifork *ifp;
> + struct xfs_attr_shortform *sf;
> + struct xfs_attr_sf_entry *sfe;
> + int offset, size, error;
> + struct xfs_mount *mp;
> + struct xfs_inode *dp;
> + struct xfs_ifork *ifp;
>
> trace_xfs_attr_sf_add(args);
>
> @@ -676,18 +724,8 @@ xfs_attr_shortform_add(xfs_da_args_t *args, int forkoff)
> ifp = dp->i_afp;
> ASSERT(ifp->if_flags & XFS_IFINLINE);
> sf = (xfs_attr_shortform_t *)ifp->if_u1.if_data;
> - sfe = &sf->list[0];
> - for (i = 0; i < sf->hdr.count; sfe = XFS_ATTR_SF_NEXTENTRY(sfe), i++) {
> -#ifdef DEBUG
> - if (sfe->namelen != args->name.len)
> - continue;
> - if (memcmp(args->name.name, sfe->nameval, args->name.len) != 0)
> - continue;
> - if (!xfs_attr_namesp_match(args->name.type, sfe->flags))
> - continue;
> - ASSERT(0);
> -#endif
> - }
> + error = xfs_attr_sf_findname(args, &sfe, NULL);
> + ASSERT(error != -EEXIST);
>
> offset = (char *)sfe - (char *)sf;
> size = XFS_ATTR_SF_ENTSIZE_BYNAME(args->name.len, args->valuelen);
> @@ -730,35 +768,26 @@ xfs_attr_fork_remove(
> * Remove an attribute from the shortform attribute list structure.
> */
> int
> -xfs_attr_shortform_remove(xfs_da_args_t *args)
> +xfs_attr_shortform_remove(struct xfs_da_args *args)
> {
> - xfs_attr_shortform_t *sf;
> - xfs_attr_sf_entry_t *sfe;
> - int base, size=0, end, totsize, i;
> - xfs_mount_t *mp;
> - xfs_inode_t *dp;
> + struct xfs_attr_shortform *sf;
> + struct xfs_attr_sf_entry *sfe;
> + int size = 0, end, totsize;
> + unsigned int base;
> + struct xfs_mount *mp;
> + struct xfs_inode *dp;
> + int error;
>
> trace_xfs_attr_sf_remove(args);
>
> dp = args->dp;
> mp = dp->i_mount;
> - base = sizeof(xfs_attr_sf_hdr_t);
> sf = (xfs_attr_shortform_t *)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->name.len)
> - continue;
> - if (memcmp(sfe->nameval, args->name.name, args->name.len) != 0)
> - continue;
> - if (!xfs_attr_namesp_match(args->name.type, sfe->flags))
> - continue;
> - break;
> - }
> - if (i == end)
> - return -ENOATTR;
> +
> + error = xfs_attr_sf_findname(args, &sfe, &base);
> + if (error != -EEXIST)
> + return error;
> + size = XFS_ATTR_SF_ENTSIZE(sfe);
>
> /*
> * Fix up the attribute fork data, covering the hole
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
> index 73615b1..0e9c87c 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.h
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
> @@ -53,6 +53,9 @@ 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_attr_sf_findname(struct xfs_da_args *args,
> + struct xfs_attr_sf_entry **sfep,
> + unsigned int *basep);
> 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
>