The owner info parameter is always NULL, so get rid of the parameter.
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NChandan Babu R <chandan.babu@oracle.com>

xfs_bmap_add_free isn't a block mapping function; it schedules deferred
freeing operations for a later point in a compound transaction chain.
While it's primarily used by bunmapi, its use has expanded beyond that.
Move it to xfs_alloc.c and rename the function since it's now general
freeing functionality.  Bring the slab cache bits in line with the
way we handle the other intent items.
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NChandan Babu R <chandan.babu@oracle.com>

Create slab caches for the high-level structures that coordinate
deferred intent items, since they're used fairly heavily.
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NChandan Babu R <chandan.babu@oracle.com>

This is a conversion of the remaining xfs_sb_version_has..(sbp)
checks to use xfs_has_..(mp) feature checks.

This was largely done with a vim replacement macro that did:

:0,$s/xfs_sb_version_has\(.*\)&\(.*\)->m_sb/xfs_has_\1\2/g<CR>

A couple of other variants were also used, and the rest touched up
by hand.

$ size -t fs/xfs/built-in.a
	   text    data     bss     dec     hex filename
before	1127533  311352     484 1439369  15f689 (TOTALS)
after	1125360  311352     484 1437196  15ee0c (TOTALS)
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>

The query_range functions are supposed to call a caller-supplied
function on each record found in the dataset.  These functions don't
own the memory storing the record, so don't let them change the record.
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Now that everything passes a perag, the agno is not needed anymore.
Convert all the users to use pag->pag_agno instead and remove the
agno from the cursor. This was largely done as an automated search
and replace.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>

Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>

Which will eventually completely replace the agno in it.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NBrian Foster <bfoster@redhat.com>

Since *init_cursor() can always return a valid cursor, the NULL check
in caller is unneeded. So clean them up.
This also keeps the behavior consistent with other callers.
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

This is much less widely used than the bc_private union was, so this
is done as a single patch. The named union xfs_btree_cur_private
goes away and is embedded into the struct xfs_btree_cur_ag as an
anonymous union, and the code is modified via this script:

$ sed -i 's/priv\.\([abt|refc]\)/\1/g' fs/xfs/*[ch] fs/xfs/*/*[ch]
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>

bc_private.a -> bc_ag conversion via script:

`sed -i 's/bc_private\.a/bc_ag/g' fs/xfs/*[ch] fs/xfs/*/*[ch]`

And then revert the change to the bc_ag #define in
fs/xfs/libxfs/xfs_btree.h manually.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>

Drop the null buffer pointer checks in all code that calls
xfs_alloc_read_agf and doesn't pass XFS_ALLOC_FLAG_TRYLOCK because
they're no longer necessary.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Convert the last of the open coded corruption check and report idioms to
use the XFS_IS_CORRUPT macro.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

The XFS_WANT_CORRUPT_* macros conceal subtle side effects such as the
creation of local variables and redirections of the code flow.  This is
pretty ugly, so replace them with explicit XFS_IS_CORRUPT tests that
remove both of those ugly points.  The change was performed with the
following coccinelle script:

@@
expression mp, test;
identifier label;
@@

- XFS_WANT_CORRUPTED_GOTO(mp, test, label);
+ if (XFS_IS_CORRUPT(mp, !test)) { error = -EFSCORRUPTED; goto label; }

@@
expression mp, test;
@@

- XFS_WANT_CORRUPTED_RETURN(mp, test);
+ if (XFS_IS_CORRUPT(mp, !test)) return -EFSCORRUPTED;

@@
expression mp, lval, rval;
@@

- XFS_IS_CORRUPT(mp, !(lval == rval))
+ XFS_IS_CORRUPT(mp, lval != rval)

@@
expression mp, e1, e2;
@@

- XFS_IS_CORRUPT(mp, !(e1 && e2))
+ XFS_IS_CORRUPT(mp, !e1 || !e2)

@@
expression e1, e2;
@@

- !(e1 == e2)
+ e1 != e2

@@
expression e1, e2, e3, e4, e5, e6;
@@

- !(e1 == e2 && e3 == e4) || e5 != e6
+ e1 != e2 || e3 != e4 || e5 != e6

@@
expression e1, e2, e3, e4, e5, e6;
@@

- !(e1 == e2 || (e3 <= e4 && e5 <= e6))
+ e1 != e2 && (e3 > e4 || e5 > e6)

@@
expression mp, e1, e2;
@@

- XFS_IS_CORRUPT(mp, !(e1 <= e2))
+ XFS_IS_CORRUPT(mp, e1 > e2)

@@
expression mp, e1, e2;
@@

- XFS_IS_CORRUPT(mp, !(e1 < e2))
+ XFS_IS_CORRUPT(mp, e1 >= e2)

@@
expression mp, e1;
@@

- XFS_IS_CORRUPT(mp, !!e1)
+ XFS_IS_CORRUPT(mp, e1)

@@
expression mp, e1, e2;
@@

- XFS_IS_CORRUPT(mp, !(e1 || e2))
+ XFS_IS_CORRUPT(mp, !e1 && !e2)

@@
expression mp, e1, e2, e3, e4;
@@

- XFS_IS_CORRUPT(mp, !(e1 == e2) && !(e3 == e4))
+ XFS_IS_CORRUPT(mp, e1 != e2 && e3 != e4)

@@
expression mp, e1, e2, e3, e4;
@@

- XFS_IS_CORRUPT(mp, !(e1 <= e2) || !(e3 >= e4))
+ XFS_IS_CORRUPT(mp, e1 > e2 || e3 < e4)

@@
expression mp, e1, e2, e3, e4;
@@

- XFS_IS_CORRUPT(mp, !(e1 == e2) && !(e3 <= e4))
+ XFS_IS_CORRUPT(mp, e1 != e2 && e3 > e4)
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Make sure we log something to dmesg whenever we return -EFSCORRUPTED up
the call stack.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Remove the return value from the functions that schedule deferred
refcount operations since they never fail and do not return status.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Remove the return value from the functions that schedule deferred rmap
operations since they never fail and do not return status.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Since no caller is using KM_NOSLEEP and no callee branches on KM_SLEEP,
we can remove KM_NOSLEEP and replace KM_SLEEP with 0.
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

There are many, many xfs header files which are included but
unneeded (or included twice) in the xfs code, so remove them.

nb: xfs_linux.h includes about 9 headers for everyone, so those
explicit includes get removed by this.  I'm not sure what the
preference is, but if we wanted explicit includes everywhere,
a followup patch could remove those xfs_*.h includes from
xfs_linux.h and move them into the files that need them.
Or it could be left as-is.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The majority of remaining references to struct xfs_defer_ops in XFS
are associated with xfs_defer_add(). At this point, there are no
more external xfs_defer_ops users left. All instances of
xfs_defer_ops are embedded in the transaction, which means we can
safely pass the transaction down to the dfops add interface.

Update xfs_defer_add() to receive the transaction as a parameter.
Various subsystems implement wrappers to allocate and construct the
context specific data structures for the associated deferred
operation type. Update these to also carry the transaction down as
needed and clean up unused dfops parameters along the way.

This removes most of the remaining references to struct
xfs_defer_ops throughout the code and facilitates removal of the
structure.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
[darrick: fix unused variable warnings with ftrace disabled]
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The dfops infrastructure ->finish_item() callback passes the
transaction and dfops as separate parameters. Since dfops is always
part of a transaction, the latter parameter is no longer necessary.
Remove it from the various callbacks.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

At this point, the transaction subsystem completely manages deferred
items internally such that the common and boilerplate
xfs_trans_alloc() -> xfs_defer_init() -> xfs_defer_finish() ->
xfs_trans_commit() sequence can be replaced with a simple
transaction allocation and commit.

Remove all such boilerplate deferred ops code. In doing so, we
change each case over to use the dfops in the transaction and
specifically eliminate:

- The on-stack dfops and associated xfs_defer_init() call, as the
  internal dfops is initialized on transaction allocation.
- xfs_bmap_finish() calls that precede a final xfs_trans_commit() of
  a transaction.
- xfs_defer_cancel() calls in error handlers that precede a
  transaction cancel.

The only deferred ops calls that remain are those that are
non-deterministic with respect to the final commit of the associated
transaction or are open-coded due to special handling.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NBill O'Donnell <billodo@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Less trivial cleanups of the error argument to xfs_btree_del_cursor;
these require some minor code refactoring.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

The error argument to xfs_btree_del_cursor already understands the
"nonzero for error" semantics, so remove pointless error testing in the
callers and pass it directly.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

All but one caller of xfs_defer_init() passes in the ->t_firstblock
of the associated transaction. The one outlier is
xlog_recover_process_intents(), which simply passes a dummy value
because a valid pointer is required. This firstblock variable can
simply be removed.

At this point we could remove the xfs_defer_init() firstblock
parameter and initialize ->t_firstblock directly. Even that is not
necessary, however, because ->t_firstblock is automatically
reinitialized in the new transaction on a transaction roll. Since
xfs_defer_init() should never occur more than once on a particular
transaction (since the corresponding finish will roll it), replace
the reinit from xfs_defer_init() with an assert that verifies the
transaction has a NULLFSBLOCK firstblock.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

xfs_refcount_recover_cow_leftovers() has no need for a firstblock
variable and so passes an unrelated xfs_fsblock_t to
xfs_defer_init() to avoid declaring one. Replace this no-op
initialization with ->t_firstblock. This will be optimized away by
the removal of the xfs_defer_init() firstblock param.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Most callers of xfs_defer_init() immediately attach the dfops
structure to a transaction. Add a transaction parameter to eliminate
much of this boilerplate code. This also helps self-document the
fact that many codepaths now expect a dfops pointer implicitly via
xfs_trans->t_dfops.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Use ->t_dfops of the leftover COW reservation cleanup transaction.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The xfs_btree_cur.bc_private.a.dfops field is only ever initialized
by the refcountbt cursor init function. The only caller of that
function with a non-NULL dfops is from deferred completion context,
which already has attached to ->t_dfops.

In addition to that, the only actual reference of a.dfops is the
cursor duplication function, which means the field is effectively
unused.

Remove the dfops field from the bc_private.a union. Any future users
can acquire the dfops from the transaction. This patch does not
change behavior.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Remove the verbose license text from XFS files and replace them
with SPDX tags. This does not change the license of any of the code,
merely refers to the common, up-to-date license files in LICENSES/

This change was mostly scripted. fs/xfs/Makefile and
fs/xfs/libxfs/xfs_fs.h were modified by hand, the rest were detected
and modified by the following command:

for f in `git grep -l "GNU General" fs/xfs/` ; do
	echo $f
	cat $f | awk -f hdr.awk > $f.new
	mv -f $f.new $f
done

And the hdr.awk script that did the modification (including
detecting the difference between GPL-2.0 and GPL-2.0+ licenses)
is as follows:

$ cat hdr.awk
BEGIN {
	hdr = 1.0
	tag = "GPL-2.0"
	str = ""
}

/^ \* This program is free software/ {
	hdr = 2.0;
	next
}

/any later version./ {
	tag = "GPL-2.0+"
	next
}

/^ \*\// {
	if (hdr > 0.0) {
		print "// SPDX-License-Identifier: " tag
		print str
		print $0
		str=""
		hdr = 0.0
		next
	}
	print $0
	next
}

/^ \* / {
	if (hdr > 1.0)
		next
	if (hdr > 0.0) {
		if (str != "")
			str = str "\n"
		str = str $0
		next
	}
	print $0
	next
}

/^ \*/ {
	if (hdr > 0.0)
		next
	print $0
	next
}

// {
	if (hdr > 0.0) {
		if (str != "")
			str = str "\n"
		str = str $0
		next
	}
	print $0
}

END { }
$
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

So we don't check the validity of records as we walk the btree. When
there are corrupt records in the free space btree (e.g. zero
startblock/length or beyond EOAG) we just blindly use it and things
go bad from there. That leads to assert failures on debug kernels
like this:

XFS: Assertion failed: fs_is_ok, file: fs/xfs/libxfs/xfs_alloc.c, line: 450
....
Call Trace:
 xfs_alloc_fixup_trees+0x368/0x5c0
 xfs_alloc_ag_vextent_near+0x79a/0xe20
 xfs_alloc_ag_vextent+0x1d3/0x330
 xfs_alloc_vextent+0x5e9/0x870

Or crashes like this:

XFS (loop0): xfs_buf_find: daddr 0x7fb28 out of range, EOFS 0x8000
.....
BUG: unable to handle kernel NULL pointer dereference at 00000000000000c8
....
Call Trace:
 xfs_bmap_add_extent_hole_real+0x67d/0x930
 xfs_bmapi_write+0x934/0xc90
 xfs_da_grow_inode_int+0x27e/0x2f0
 xfs_dir2_grow_inode+0x55/0x130
 xfs_dir2_sf_to_block+0x94/0x5d0
 xfs_dir2_sf_addname+0xd0/0x590
 xfs_dir_createname+0x168/0x1a0
 xfs_rename+0x658/0x9b0

By checking that free space records pulled from the trees are
within the valid range, we catch many of these corruptions before
they can do damage.

This is a generic btree record checking deficiency. We need to
validate the records we fetch from all the different btrees before
we use them to catch corruptions like this.

This patch results in a corrupt record emitting an error message and
returning -EFSCORRUPTED, and the higher layers catch that and abort:

 XFS (loop0): Size Freespace BTree record corruption in AG 0 detected!
 XFS (loop0): start block 0x0 block count 0x0
 XFS (loop0): Internal error xfs_trans_cancel at line 1012 of file fs/xfs/xfs_trans.c.  Caller xfs_create+0x42a/0x670
 .....
 Call Trace:
  dump_stack+0x85/0xcb
  xfs_trans_cancel+0x19f/0x1c0
  xfs_create+0x42a/0x670
  xfs_generic_create+0x1f6/0x2c0
  vfs_create+0xf9/0x180
  do_mknodat+0x1f9/0x210
  do_syscall_64+0x5a/0x180
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
.....
 XFS (loop0): xfs_do_force_shutdown(0x8) called from line 1013 of file fs/xfs/xfs_trans.c.  Return address = ffffffff81500868
 XFS (loop0): Corruption of in-memory data detected.  Shutting down filesystem
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

generic/475 fired an assert failure just after the filesystem was
shut down:

XFS: Assertion failed: fs_is_ok, file: fs/xfs/libxfs/xfs_refcount.c, line: 182
.....
Call Trace:
 xfs_refcount_insert+0x151/0x190
 xfs_refcount_adjust_extents.constprop.11+0x9c/0x470
 xfs_refcount_adjust.constprop.10+0xb0/0x270
 xfs_refcount_finish_one+0x25a/0x420
 xfs_trans_log_finish_refcount_update+0x2a/0x40
 xfs_refcount_update_finish_item+0x35/0xa0
 xfs_defer_finish+0x15e/0x4d0
 xfs_reflink_remap_extent+0x1bc/0x610
 xfs_reflink_remap_blocks+0x6e/0x280
 xfs_reflink_remap_range+0x311/0x530
 vfs_clone_file_range+0x119/0x200
 ....

If xfs_btree_insert() returns an error, the corruption check fires
instead of passing the error back the caller. The corruption check
should be after we've checked for an error, not before, thereby
avoiding assert failures if the filesystem shuts down during a
refcount btree record insert.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Add a couple of functions to the refcount btree and generic btree code
that will be used to repair the refcountbt.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Expose various helpers that the repair code will want to use.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Add a couple of functions to the refcount btrees that will be used
to cross-reference metadata against the refcountbt.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Under the deferred rmap operation scheme, there's a certain order in
which the rmap deferred ops have to be queued to maintain integrity
during log replay.  For alloc/map operations that order is cui -> rui;
for free/unmap operations that order is cui -> rui -> efi.  However, the
initial refcount code got the ordering wrong in the free side of things
because it queued refcount free op and an EFI and the refcount free op
queued a rmap free op, resulting in the order cui -> efi -> rui.

If we fail before the efd finishes, the efi recovery will try to do a
wildcard rmap removal and the subsequent rui will fail to find the rmap
and blow up.  This didn't ever happen due to other screws up in handling
unknown owner rmap removals, but those other screw ups broke recovery in
other ways, so fix the ordering to follow the intended rules.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Move the error injection tag names into a libxfs header so that we can
share it between kernel and userspace.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

And instead require callers to explicitly join the inode using
xfs_defer_ijoin.  Also consolidate the defer error handling in
a few places using a goto label.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

In some circumstances, _alloc_read_agf can return an error code of zero
but also a null AGF buffer pointer.  Check for this and jump out.

Fixes-coverity-id: 1415250
Fixes-coverity-id: 1415320
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>