On Thu, Sep 19, 2019 at 04:51:02PM -0700, Allison Collins wrote:
>
>
> On 9/19/19 10:47 AM, Brian Foster wrote:
> > On Thu, Sep 05, 2019 at 03:18:22PM -0700, Allison Collins wrote:
> > > From: Allison Henderson <allison.henderson@xxxxxxxxxx>
> > >
> > > 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 appearence of duplicated code. We will
> > > need these routines later for delayed attributes since delayed
> > > operations cannot return error codes.
> > >
> > > Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> > > Signed-off-by: Allison Collins <allison.henderson@xxxxxxxxxx>
> >
> > Extra s-o-b tag?
> Oops, I thought I had caught all the old names. Will clean out :-)
>
> >
> > > ---
> > > fs/xfs/libxfs/xfs_attr.c | 150 +++++++++++++++++++++++++++---------------
> > > fs/xfs/libxfs/xfs_attr.h | 1 +
> > > fs/xfs/libxfs/xfs_attr_leaf.c | 92 +++++++++++++++++---------
> > > fs/xfs/libxfs/xfs_attr_leaf.h | 2 +
> > > 4 files changed, 161 insertions(+), 84 deletions(-)
> > >
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index 50e099f..a297857 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > > @@ -46,6 +46,7 @@ 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);
> > > STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
> > > +STATIC int xfs_leaf_has_attr(struct xfs_da_args *args, struct xfs_buf **bp);
> >
> > The fact that this is not named xfs_attr_leaf_*() kind of stands out
> > here, particularly since the node variant uses the xfs_attr_* prefix.
> > Hm? (Same goes for xfs_shortform_has_attr() I suppose..).
> Sure, I can flip the prefixes around to look a little more consistent
> >
> > > /*
> > > * Internal routines when attribute list is more than one block.
> > > @@ -53,6 +54,8 @@ STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
> > > STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> > > STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
> > > STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
> > > +STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
> > > + struct xfs_da_state **state);
> > > STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
> > > STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
> > > @@ -309,6 +312,32 @@ 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;
> > > + 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, NULL, NULL);
> > > + } else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> > > + error = xfs_leaf_has_attr(args, &bp);
> > > + xfs_trans_brelse(args->trans, bp);
> > > + } else {
> > > + error = xfs_attr_node_hasname(args, NULL);
> > > + }
> > > +
> > > + return error;
> > > +}
> > > +
> >
> > FWIW, I think it's preferable to include new functions like this with
> > the first user. I'm a bit curious about the use of error codes here as
> > opposed to returning a boolean. I could see being able to handle
> > unexpected errors as a good reason for doing that, but taking a quick
> > look ahead, it appears neither caller of xfs_has_attr() does so. ;)
> >
> > (To be clear, I think keeping the function as is and fixing up the
> > eventual callers to handle unexpected errors is probably the right thing
> > to do.).
>
> The new top level function actually doesnt get used until patch 18, but I
> guess I try to keep the patch sizes small to make them easier for people to
> review. Basically we use it to see if there is/isnt an attribute present,
> and then return the appropriate error code right away. IE, trying to remove
> an attribute that isnt there immediately return EENOATTR rather than trying
> to start a delayed operation that isnt going to be successful. The is
> because delayed operations are not supposed to return error codes. If they
> do, they cause a shut down, which is not correct here.
>
Makes sense. It might be fine to leave the associated refactoring and
just defer the new helper to the later patch, fwiw.
> Initially I think I had it returning booleans, but it means the top level
> function needs to do extra handling to translate the error codes, and I
> thought it looked messy. So I decided to stick with the scheme that the
> rest of the code was using.
>
Yeah, it's strange at first, but seems prevalent throughout the xattr
code. Perhaps that's something we can clean up a bit down the road.
> I skipped ahead about unexpected error codes and see what you mean, so I
> will add some extra handlers there.
>
> >
> > > +/*
> > > * Remove the attribute specified in @args.
> > > */
> > > int
> > > @@ -574,26 +603,17 @@ 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, -1, &bp);
> > > - if (error)
> > > - return error;
> > > -
> >
> > It looks like we lose this unexpected error check here (i.e. suppose we
> > got -ENOMEM or -EFSCORRUPTED or something that indicates we shouldn't
> > continue). FWIW, this seems to repeat throughout this patch where we've
> > invoked the new helpers..
>
> Ok, I'll add in an explicit check for (retval != -ENOATTR && retval !=
> -EEXIST)
>
>
> >
> > > - /*
> > > * 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_leaf_has_attr(args, &bp);
> > > if ((args->name.type & ATTR_REPLACE) && (retval == -ENOATTR)) {
> > > xfs_trans_brelse(args->trans, bp);
> > > return retval;
> > > @@ -745,6 +765,25 @@ xfs_attr_leaf_addname(
> > > }
> > > /*
> > > + * Return EEXIST 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;
> >
> > This seems misplaced for a helper, but I could be missing context. Why
> > not just pass zero directly and leave the args->blkno assignment to the
> > caller?
> I guess just I kept these two lines together since that's was how they
> initially appeared before factoring them out, but it does look a bit off.
> It should be ok leave the assignment to the caller. I can push it back up.
>
> >
> > > + error = xfs_attr3_leaf_read(args->trans, args->dp,
> > > + args->blkno, XFS_DABUF_MAP_NOMAPPING, bp);
> > > + if (error)
> > > + return error;
> > > +
> > > + return xfs_attr3_leaf_lookup_int(*bp, args);
> > > +}
> > > +
> > > +/*
> > > * Remove a name from the leaf attribute list structure
> > > *
> > > * This leaf block cannot have a "remote" value, we only call this routine
> > > @@ -764,12 +803,8 @@ xfs_attr_leaf_removename(
> > > * Remove the attribute.
> > > */
> > > dp = args->dp;
> > > - args->blkno = 0;
> > > - error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno, -1, &bp);
> > > - if (error)
> > > - return error;
> >
> > Lost error check.
> >
> > > - error = xfs_attr3_leaf_lookup_int(bp, args);
> > > + error = xfs_leaf_has_attr(args, &bp);
> > > if (error == -ENOATTR) {
> > > xfs_trans_brelse(args->trans, bp);
> > > return error;
> > > @@ -808,12 +843,7 @@ 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, -1, &bp);
> > > - if (error)
> > > - return error;
> > > -
> >
> > ^ here too. Not sure if I caught them all, but you get the idea. ;)
> Ok,I'll sweep through and find them :-)
>
> >
> > > - error = xfs_attr3_leaf_lookup_int(bp, args);
> > > + error = xfs_leaf_has_attr(args, &bp);
> > > if (error != -EEXIST) {
> > > xfs_trans_brelse(args->trans, bp);
> > > return error;
> > > @@ -823,6 +853,43 @@ 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;
> > > + 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;
> > > +
> >
> > No real need for the dp local variable here if it's just to reference
> > ->i_mount. Also I know that comment isn't introduced by this patch, but
> > any idea what it actually means? It doesn't make much sense to me at a
> > glance. :P
>
> Ok, will clean out assignment. I'm actually not sure as to the comments
> origins either, I assumed it was in reference the the state? I suppose
> state is used to keep track of a lot of things going on in the calling
> function. But even in that context, I don't find the comment particularly
> descriptive. Should I clean it out?
>
Unless somebody can chime in and explain what it means (so perhaps we
could reword it), I'd probably just remove it.
Brian
> >
> > > + /*
> > > + * Search to see if name exists, and get back a pointer to it.
> > > + */
> > > + error = xfs_da3_node_lookup_int(state, &retval);
> > > + if (error == 0)
> > > + error = retval;
> > > +
> > > + if (statep != NULL)
> > > + *statep = state;
> > > + else
> > > + xfs_da_state_free(state);
> > > +
> > > + return error;
> > > +}
> > > +
> > > /*========================================================================
> > > * External routines when attribute list size > geo->blksize
> > > *========================================================================*/
> > > @@ -855,17 +922,14 @@ 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)
> >
> > Error check again.
> >
> > > + error = xfs_attr_node_hasname(args, &state);
> > > + if (error == -EEXIST)
> > > goto out;
> > > +
> > > blk = &state->path.blk[ state->path.active-1 ];
> > > ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
> > > if ((args->name.type & ATTR_REPLACE) && (retval == -ENOATTR)) {
> > > @@ -1070,29 +1134,15 @@ 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.
> > > @@ -1314,20 +1364,14 @@ xfs_attr_node_get(xfs_da_args_t *args)
> > > 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) {
> > > + error = xfs_attr_node_hasname(args, &state);
> > > + if (error != -EEXIST) {
> > > retval = error;
> > > goto out_release;
> > > }
> > > - if (retval != -EEXIST)
> > > - goto out_release;
> > > /*
> > > * Get the value, local or "remote"
> > > diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> > > index cedb4e2..fb56d81 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 xfs_attr_set_args(struct xfs_da_args *args);
> > > int xfs_attr_remove(struct xfs_inode *dp, struct xfs_name *name);
> > > +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 07ce320..a501538 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> > > +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> > > @@ -590,6 +590,53 @@ 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
> > > + * basep: If not null, pointer is set to the byte offset of the entry in the
> > > + * list
> > > + */
> > > +int
> > > +xfs_shortform_has_attr(
> > > + struct xfs_da_args *args,
> > > + struct xfs_attr_sf_entry **sfep,
> > > + int *basep)
> > > +{
> > > + 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;
> > > +
> > > + base = sizeof(struct xfs_attr_sf_hdr);
> > > + 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;
> >
> > This function seems like it could just return a bool. Eh, I suppose it's
> > better to be consistent with the other variants if those ones can return
> > unrelated errors.
> Ok, I prefer the consistency as well.
>
> >
> > > +}
> > > +
> > > +/*
> > > * Add a name/value pair to the shortform attribute list.
> > > * Overflow from the inode has already been checked for.
> > > */
> > > @@ -598,7 +645,7 @@ xfs_attr_shortform_add(xfs_da_args_t *args, int forkoff)
> > > {
> > > xfs_attr_shortform_t *sf;
> > > xfs_attr_sf_entry_t *sfe;
> > > - int i, offset, size;
> > > + int offset, size, error;
> > > xfs_mount_t *mp;
> > > xfs_inode_t *dp;
> >
> > Nit: might be good to clean up the typedefs here since you do it in the
> > remove function as well.
> Sure, will do.
>
> >
> > > struct xfs_ifork *ifp;
> > > @@ -612,18 +659,10 @@ 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++) {
> > > + error = xfs_shortform_has_attr(args, &sfe, NULL);
> > > #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);
> > > + ASSERT(error != -EEXIST);
> > > #endif
> >
> > Hmm, interesting. So basically this code walks to the end of the list
> > for the purpose of placement of the new attr and the debug code simply
> > asserts that we don't find an existing attr. The only thing that
> > concerns me is that nothing about xfs_shortform_has_attr() indicates
> > that the output values are important when the lookup fails. The comment
> > only explains what the values are when a lookup succeeds. Could we
> > update the comment to elaborate on this use case to prevent somebody
> > from unknowingly breaking it down the road?
> >
> > Also, there's no need for the #ifdef DEBUG any more with just the assert
> > check in that block.
>
> Sure, I will clearify the comments and pull out the DEBUG
>
> >
> > > - }
> > > offset = (char *)sfe - (char *)sf;
> > > size = XFS_ATTR_SF_ENTSIZE_BYNAME(args->name.len, args->valuelen);
> > > @@ -668,33 +707,24 @@ xfs_attr_fork_remove(
> > > int
> > > xfs_attr_shortform_remove(xfs_da_args_t *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;
> >
> > This value of end is unused (end is immediately reassigned further down
> > in the function).
> >
> > Brian
>
> Ok, I will pick that out. Thank you for the thorough reviews!
>
> Allison
>
> >
> > > - 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_shortform_has_attr(args, &sfe, &base);
> > > + if (error == -ENOATTR)
> > > + 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 536a290..58e9327 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_leaf.h
> > > +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
> > > @@ -42,6 +42,8 @@ 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,
> > > + struct xfs_attr_sf_entry **sfep, 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
> > >
