Old kernels did not zero the pad field in xfs_dir3_data_hdr when
initializing directory data blocks, so existing filesystems may have
non-zero padding on disk.

Zero the pad field in xfs_dir3_data_write_verify alongside the existing
LSN and checksum updates. The pad field is pure alignment padding with
no runtime meaning, so zeroing it during write verification is safe and
has no additional I/O cost. This lets filesystems gradually self-heal
stale non-zero padding as directories are modified, without requiring an
explicit repair pass.

Suggested-by: Dave Chinner <dgc@kernel.org>
Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

xfs_dir3_data_init currently zeroes only the xfs_dir3_blk_hdr portion of
the directory data block header, then manually initializes the bestfree
entries in a loop. This leaves the pad field in xfs_dir3_data_hdr
uninitialized and requires explicit zeroing of each bestfree slot.

Zero the entire header region (geo->data_entry_offset bytes)
unconditionally before setting individual fields. This covers all
current and future header fields, all padding (implicit and explicit),
and the bestfree array, so the manual zeroing loop for bestfree can be
removed.

Suggested-by: Dave Chinner <dgc@kernel.org>
Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

In xfs_refcount_finish_one(), there's no need to pass
XFS_ALLOC_FLAG_FREEING to xfs_alloc_read_agf().

So remove it.

Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

The per-AG buffer hashes were added when all buffer lookups took a
per-hash look.  Since then we've made lookups entirely lockless and
removed the need for a hash-wide lock for inserts and removals as
well.  With this there is no need to sharding the hash, so reduce the
used resources by using a per-buftarg hash for all buftargs.

Long after writing this initially, syzbot found a problem in the buffer
cache teardown order, which this happens to fix as well by doing the
entire buffer cache teardown in one places instead of splitting it
between destroying the buftarg and the perag structures.

Link: https://lore.kernel.org/linux-xfs/aLeUdemAZ5wmtZel@dread.disaster.area/
Reported-by: syzbot+0391d34e801643e2809b@syzkaller.appspotmail.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: syzbot+0391d34e801643e2809b@syzkaller.appspotmail.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Signed-off-by: Carlos Maiolino <cem@kernel.org>

Factor out wrapper xfs_attr3_leaf_init function, which exported for
external use.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Long Li <leo.lilong@huawei.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Factor out wrapper xfs_attr3_node_entry_remove function, which
exported for external use.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Long Li <leo.lilong@huawei.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Signed-off-by: Carlos Maiolino <cem@kernel.org>

Add the `__counted_by_ptr` attribute to the `buffer` field of `struct
xfs_attr_list_context`. This field is used to point to a buffer of
size `bufsize`.

The `buffer` field is assigned in:
1. `xfs_ioc_attr_list` in `fs/xfs/xfs_handle.c`
2. `xfs_xattr_list` in `fs/xfs/xfs_xattr.c`
3. `xfs_getparents` in `fs/xfs/xfs_handle.c` (implicitly initialized to NULL)

In `xfs_ioc_attr_list`, `buffer` was assigned before `bufsize`. Reorder
them to ensure `bufsize` is set before `buffer` is assigned, although
no access happens between them.

In `xfs_xattr_list`, `buffer` was assigned before `bufsize`. Reorder
them to ensure `bufsize` is set before `buffer` is assigned.

In `xfs_getparents`, `buffer` is NULL (from zero initialization) and
remains NULL. `bufsize` is set to a non-zero value, but since `buffer`
is NULL, no access occurs.

In all cases, the pointer `buffer` is not accessed before `bufsize` is set.

This patch was generated by CodeMender and reviewed by Bill Wendling.
Tested by running xfstests.

Signed-off-by: Bill Wendling <morbo@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

xfs_defer_can_append returns a bool, it shouldn't be returning
a NULL.

Found by code inspection.

Fixes: 4dffb2cbb483 ("xfs: allow pausing of pending deferred work items")
Cc: <stable@vger.kernel.org> # v6.8
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Acked-by: Souptick Joarder <souptick.joarder@hpe.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>