Re: [PATCH v5 04/14] xfs: Add xfs_has_attr and subroutines

Brian Foster
2019-12-13T20:37:11Z

On Wed, Dec 11, 2019 at 09:15:03PM -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 | 166 +++++++++++++++++++++++++++---------------
> fs/xfs/libxfs/xfs_attr.h | 1 +
> fs/xfs/libxfs/xfs_attr_leaf.c | 110 +++++++++++++++++-----------
> fs/xfs/libxfs/xfs_attr_leaf.h | 3 +
> 4 files changed, 182 insertions(+), 98 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 9628ed8..88de43c 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
...
> @@ -310,6 +313,36 @@ 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;
> +
> + 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);
> + }
> +
> + if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> + struct xfs_buf *bp = NULL;
> + int error = xfs_attr_leaf_hasname(args, &bp);
> +

I'd prefer to not obfuscate function calls in variable declarations like
this. I'd say just declare bp and error at the top and let this be:

error = xfs_attr_leaf_hasname(...)

> + if (bp)
> + xfs_trans_brelse(args->trans, bp);
> +
> + return error;
> + }
> +
> + return xfs_attr_node_hasname(args, NULL);
> +}
> +
> +/*
> * Remove the attribute specified in @args.
> */
> int
> @@ -583,26 +616,20 @@ STATIC int
> xfs_attr_leaf_addname(
> struct xfs_da_args *args)
> {
> - struct xfs_inode *dp;
> struct xfs_buf *bp;
> int retval, error, forkoff;
> + struct xfs_inode *dp = args->dp;
>
> trace_xfs_attr_leaf_addname(args);
>
> /*
> - * Read the (only) block in the attribute list in.
> - */
> - dp = args->dp;
> - args->blkno = 0;
> - error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, &bp);
> - if (error)
> - return error;
> -
> - /*
> * Look up the given attribute in the leaf block. Figure out if
> * the given flags produce an error or call for an atomic rename.
> */
> - retval = xfs_attr3_leaf_lookup_int(bp, args);
> + retval = xfs_attr_leaf_hasname(args, &bp);
> + if (retval != -ENOATTR && retval != -EEXIST)
> + return retval;
> +

Do we need to call xfs_trans_brelse() in certain cases before we return?
For example, consider if the read succeeds but the lookup returns
something other than -ENOATTR or -EEXIST. Perhaps the _hasname() func
should just call brelse() itself if it's returning an unexpected error
after reading in the buf so the caller doesn't need to care about it..

> if ((args->name.type & ATTR_REPLACE) && (retval == -ENOATTR)) {
> xfs_trans_brelse(args->trans, bp);
> return retval;
...
> @@ -864,20 +940,17 @@ xfs_attr_node_addname(
> dp = args->dp;
> mp = dp->i_mount;
> restart:
> - state = xfs_da_state_alloc();
> - state->args = args;
> - state->mp = mp;
> -
> /*
> * Search to see if name already exists, and get back a pointer
> * to where it should go.
> */
> - error = xfs_da3_node_lookup_int(state, &retval);
> - if (error)
> + retval = xfs_attr_node_hasname(args, &state);
> + if (retval != -ENOATTR)
> goto out;

The else case below checks for -EEXIST, but it looks like we'd return
here..

Brian

> +
> blk = &state->path.blk[ state->path.active-1 ];
> ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
> - if ((args->name.type & ATTR_REPLACE) && (retval == -ENOATTR)) {
> + if (args->name.type & ATTR_REPLACE) {
> goto out;
> } else if (retval == -EEXIST) {
> if (args->name.type & ATTR_CREATE)
> @@ -1079,29 +1152,15 @@ xfs_attr_node_removename(
> {
> struct xfs_da_state *state;
> struct xfs_da_state_blk *blk;
> - struct xfs_inode *dp;
> struct xfs_buf *bp;
> int retval, error, forkoff;
> + struct xfs_inode *dp = args->dp;
>
> trace_xfs_attr_node_removename(args);
>
> - /*
> - * 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;
> + error = xfs_attr_node_hasname(args, &state);
> + if (error != -EEXIST)
> goto out;
> - }
>
> /*
> * If there is an out-of-line value, de-allocate the blocks.
> @@ -1196,7 +1255,8 @@ xfs_attr_node_removename(
> error = 0;
>
> out:
> - xfs_da_state_free(state);
> + if (state)
> + xfs_da_state_free(state);
> return error;
> }
>
> @@ -1316,31 +1376,23 @@ 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 +1404,7 @@ xfs_attr_node_get(xfs_da_args_t *args)
> }
>
> xfs_da_state_free(state);
> - return retval;
> + return error;
> }
>
> /* Returns true if the attribute entry name is valid. */
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 44dd07a..3b5dad4 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -150,6 +150,7 @@ int xfs_attr_set(struct xfs_inode *dp, struct xfs_name *name,
> unsigned char *value, int valuelen, int flags);
> int xfs_attr_set_args(struct xfs_da_args *args);
> int xfs_attr_remove(struct xfs_inode *dp, struct xfs_name *name, int flags);
> +int xfs_has_attr(struct xfs_da_args *args);
> int xfs_attr_remove_args(struct xfs_da_args *args);
> 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 5465446..ef96971 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++) {
> + 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 +768,25 @@ 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 base, size = 0, end, totsize;
> + 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 f4a188e..f6165ff 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.h
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
> @@ -62,6 +62,9 @@ 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
>