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

Allison Collins
2019-12-14T06:58:39Z

On 12/13/19 6:08 AM, Brian Foster wrote:
> 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:
Sure, this style was a suggestion from Christoph in the last review so I
tried to combine everyones requests as best as possible. I'm not very
particular about the aesthetics, so I don't mind moving things around,
but if people feel strongly one way or another, please chime in.

>
> 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..
Generally it should be released at some point if the call is successful
(so on -EEXIST). Later when we get into the state machine, we don't
release right away, because we need to hold it across the transaction rolls.

I think though I might be able to factor up releasing the buffer on
error though. I'll see if I can work that into the next version.

>
>> 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

Ok, will clean out. Thx!
Allison

>
>> +
>> 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
>>
>