Merge tag 'vfs-7.2-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - netfs:

    - fix the decision when to disallow write-streaming with fscache in
      use, handling of asynchronous cache object creation, a double fput
      in cachefiles, clearing S_KERNEL_FILE without the inode lock held,
      page extraction bugs in the iov_iter helpers (a potential
      underflow, a missing allocation failure check, a memory leak, and
      a folio offset miscalculation), writeback error and ENOMEM
      handling, DIO write retry for filesystems without a
      ->prepare_write() method, and the replacement of the wb_lock mutex
      with a bit lock plus writethrough collection offload so that
      multiple asynchronous writebacks don't interfere with each other.

    - Fix the barriering when walking the netfs subrequest list during
      retries as it was possible to see a subrequest that was just added
      by the application thread.

 - iomap:

    - Change iomap to submit read bios after each extent instead of
      building them up across extents. The old behavior was considered
      problematic for a while and now caused an actual erofs bug.

    - Guard the ioend io_size EOF trim in iomap against underflow when a
      concurrent truncate moves EOF below the start of the ioend,
      wrapping io_size to a huge value.

 - overlayfs

    - Fix a stale overlayfs comment about the locking order.

    - Store the linked-in upper dentry instead of the disconnected
      O_TMPFILE dentry during overlayfs tmpfile copy-up. With a FUSE or
      virtiofs upper layer ->d_revalidate() would try to look up "/" in
      the workdir and fail, causing persistent ESTALE errors that broke
      dpkg and apt.

 - vfs-bpf:

   Have the bpf_real_data_inode() kfunc take a struct file instead of a
   dentry so it is usable from the bprm_check_security, mmap_file, and
   file_mprotect hooks, and rename it from bpf_real_inode() to make the
   data-inode semantics explicit. The kfunc landed this cycle so the
   change is safe.

 - afs:

   NULL pointer dereferences in the callback service and in
   afs_get_tree(), several memory and refcount leaks, missing locking
   around the dynamic root inode numbers and premature cell exposure
   through /afs, a netns destruction hang caused by a misplaced
   increment of net->cells_outstanding, a bulk lookup malfunction caused
   by the dir_emit() API change, inode (re)initialisation issues, and
   assorted smaller fixes to error codes, seqlock handling, and debug
   output.

 - vfs:

   Refuse O_TMPFILE creation with an unmapped fsuid or fsgid and add a
   selftest for it.

 - vboxsf:

   Add Jori Koolstra as vboxsf maintainer, taking over from Hans de
   Goede.

 - dio:

   Release the pages attached to a short atomic dio bio; the REQ_ATOMIC
   size check error path leaked them.

 - procfs:

   Only bump the parent directory link count when registering
   directories in procfs. Registering regular files inflated the count
   and leaked a link on every create and remove cycle.

 - minix:

   Avoid an unsigned overflow in the minix bitmap block count
   calculation that let crafted images with huge inode or zone counts
   pass superblock validation and crash the kernel during mount.

 - cachefiles:

   Fix a double unlock in the cachefiles nomem_d_alloc error path left
   over from the start_creating() conversion.

 - fat:

   Stop fat from reading directory entries past the 0x00
   end-of-directory marker. If the trailing on-disk slots aren't
   zero-filled the driver surfaced arbitrary garbage as directory
   entries.

 - freexvfs:

   Don't BUG() on unknown typed-extent types in freevxfs, reachable via
   ioctl(FIBMAP) on a crafted image; fail with an I/O error instead.

 - orangefs:

   Keep the readdir entry size 64-bit in orangefs fill_from_part().
   Truncating it to __u32 bypassed the bounds check and led to
   out-of-bounds reads triggerable by the userspace client.

 - xfs:

   Fix the error unwind in xfs_open_devices() which released the rt
   device file twice and left dangling buftarg pointers behind that were
   freed again when the failed mount was torn down.

 - exec:

   Fix an off-by-one in the comment documenting the maximum binfmt
   rewrite depth in exec_binprm(). The code allows five rewrites, not
   four; restricting the code would break userspace so the comment is
   fixed instead.

 - file handles:

   Reject detached mounts in capable_wrt_mount(). A detached mount can
   be dissolved concurrently, leaving a NULL mount namespace that
   open_by_handle_at() would dereference.

* tag 'vfs-7.2-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (57 commits)
  netfs: Fix barriering when walking subrequest list
  iomap: submit read bio after each extent
  fuse: call fuse_send_readpages explicitly from fuse_readahead
  iomap: consolidate bio submission
  fhandle: reject detached mounts in capable_wrt_mount()
  netfs: Fix DIO write retry for filesystems without a ->prepare_write()
  netfs: Fix folio state after ENOMEM whilst under writeback iteration
  netfs: Fix writeback error handling
  netfs: Fix writethrough to use collection offload
  netfs: Replace wb_lock with a bit lock for asynchronicity
  netfs: Fix kdoc warning
  scatterlist: Fix offset in folio calc in extract_xarray_to_sg()
  iov_iter: Remove unused variable in kunit_iov_iter.c
  iov_iter: Fix a memory leak in iov_iter_extract_user_pages()
  iov_iter: Fix missing alloc fail check in iov_iter_extract_bvec_pages()
  iov_iter: Fix potential underflow in iov_iter_extract_xarray_pages()
  cachefiles: Fix file burial to take lock when unsetting S_KERNEL_FILE
  cachefiles: Fix double fput
  netfs: Fix netfs_create_write_req() to handle async cache object creation
  netfs: Fix decision whether to disallow write-streaming due to fscache use
  ...

2 files changed, 12 insertions, 3 deletions

diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 3582ed1fe236..56b43d594e6e 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -622,6 +622,8 @@ extern struct bio_set iomap_ioend_bioset;
 #ifdef CONFIG_BLOCK
 int iomap_bio_read_folio_range(const struct iomap_iter *iter,
 		struct iomap_read_folio_ctx *ctx, size_t plen);
+void iomap_bio_submit_read_endio(const struct iomap_iter *iter,
+		struct iomap_read_folio_ctx *ctx, bio_end_io_t end_io);
 
 extern const struct iomap_read_ops iomap_bio_read_ops;
 
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 243c0f737938..1bc120d61c5b 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -61,14 +61,16 @@ struct netfs_inode {
 #if IS_ENABLED(CONFIG_FSCACHE)
 	struct fscache_cookie	*cache;
 #endif
-	struct mutex		wb_lock;	/* Writeback serialisation */
+	struct list_head	wb_queue;	/* Queue of processes wanting to do writeback */
 	loff_t			_remote_i_size;	/* Size of the remote file */
 	loff_t			_zero_point;	/* Size after which we assume there's no data
 						 * on the server */
+	spinlock_t		lock;		/* Lock covering wb_queue */
 	atomic_t		io_count;	/* Number of outstanding reqs */
 	unsigned long		flags;
 #define NETFS_ICTX_ODIRECT	0		/* The file has DIO in progress */
 #define NETFS_ICTX_UNBUFFERED	1		/* I/O should not use the pagecache */
+#define NETFS_ICTX_WB_LOCK	2		/* Writeback serialisation lock */
 #define NETFS_ICTX_MODIFIED_ATTR 3		/* Indicate change in mtime/ctime */
 #define NETFS_ICTX_SINGLE_NO_UPLOAD 4		/* Monolithic payload, cache but no upload */
 };
@@ -462,6 +464,10 @@ int netfs_alloc_folioq_buffer(struct address_space *mapping,
 			      size_t *_cur_size, ssize_t size, gfp_t gfp);
 void netfs_free_folioq_buffer(struct folio_queue *fq);
 
+/* Writeback exclusion API. */
+bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait);
+void netfs_wb_end(struct netfs_inode *ictx);
+
 /**
  * netfs_inode - Get the netfs inode context from the inode
  * @inode: The inode to query
@@ -743,7 +749,8 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,
 #if IS_ENABLED(CONFIG_FSCACHE)
 	ctx->cache = NULL;
 #endif
-	mutex_init(&ctx->wb_lock);
+	INIT_LIST_HEAD(&ctx->wb_queue);
+	spin_lock_init(&ctx->lock);
 	/* ->releasepage() drives zero_point */
 	if (use_zero_point) {
 		ctx->_zero_point = ctx->_remote_i_size;
@@ -753,7 +760,7 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,
 
 /**
  * netfs_resize_file - Note that a file got resized
- * @ctx: The netfs inode being resized
+ * @ictx: The netfs inode being resized
  * @new_i_size: The new file size
  * @changed_on_server: The change was applied to the server
  *