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

Allison Henderson
2019-04-22T22:01:35Z

On 4/22/19 6:00 AM, Brian Foster wrote:
> 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

Sure, I will see if I can factor out the common code and consolidate
things a bit.

Allison

>
>> +
>> + 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
>>