Merge tag 'vfs-6.12-rc2.fixes.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
 "vfs:

   - Ensure that iter_folioq_get_pages() advances to the next slot
     otherwise it will end up using the same folio with an out-of-bound
     offset.

  iomap:

   - Dont unshare delalloc extents which can't be reflinked, and thus
     can't be shared.

   - Constrain the file range passed to iomap_file_unshare() directly in
     iomap instead of requiring the callers to do it.

  netfs:

   - Use folioq_count instead of folioq_nr_slot to prevent an
     unitialized value warning in netfs_clear_buffer().

   - Fix missing wakeup after issuing writes by scheduling the write
     collector only if all the subrequest queues are empty and thus no
     writes are pending.

   - Fix two minor documentation bugs"

* tag 'vfs-6.12-rc2.fixes.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  iomap: constrain the file range passed to iomap_file_unshare
  iomap: don't bother unsharing delalloc extents
  netfs: Fix missing wakeup after issuing writes
  Documentation: add missing folio_queue entry
  folio_queue: fix documentation
  netfs: Fix a KMSAN uninit-value error in netfs_clear_buffer
  iov_iter: fix advancing slot in iter_folioq_get_pages()

Author: torvalds

Documentation/core-api/index.rst

@@ -37,6 +37,7 @@ Library functionality that is used throughout the kernel.
    kref
    cleanup
    assoc_array
+   folio_queue
    xarray
    maple_tree
    idr

fs/dax.c

@@ -1305,11 +1305,15 @@ int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 	struct iomap_iter iter = {
 		.inode		= inode,
 		.pos		= pos,
-		.len		= len,
 		.flags		= IOMAP_WRITE | IOMAP_UNSHARE | IOMAP_DAX,
 	};
+	loff_t size = i_size_read(inode);
 	int ret;
 
+	if (pos < 0 || pos >= size)
+		return 0;
+
+	iter.len = min(len, size - pos);
 	while ((ret = iomap_iter(&iter, ops)) > 0)
 		iter.processed = dax_unshare_iter(&iter);
 	return ret;

fs/iomap/buffered-io.c

@@ -1321,7 +1321,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 		return length;
 
 	/*
-	 * Don't bother with holes or unwritten extents.
+	 * Don't bother with delalloc reservations, holes or unwritten extents.
 	 *
 	 * Note that we use srcmap directly instead of iomap_iter_srcmap as
 	 * unsharing requires providing a separate source map, and the presence
@@ -1330,6 +1330,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 	 * fork for XFS.
 	 */
 	if (iter->srcmap.type == IOMAP_HOLE ||
+	    iter->srcmap.type == IOMAP_DELALLOC ||
 	    iter->srcmap.type == IOMAP_UNWRITTEN)
 		return length;
 
@@ -1374,11 +1375,15 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 	struct iomap_iter iter = {
 		.inode		= inode,
 		.pos		= pos,
-		.len		= len,
 		.flags		= IOMAP_WRITE | IOMAP_UNSHARE,
 	};
+	loff_t size = i_size_read(inode);
 	int ret;
 
+	if (pos < 0 || pos >= size)
+		return 0;
+
+	iter.len = min(len, size - pos);
 	while ((ret = iomap_iter(&iter, ops)) > 0)
 		iter.processed = iomap_unshare_iter(&iter);
 	return ret;

fs/netfs/misc.c

@@ -102,7 +102,7 @@ void netfs_clear_buffer(struct netfs_io_request *rreq)
 
 	while ((p = rreq->buffer)) {
 		rreq->buffer = p->next;
-		for (int slot = 0; slot < folioq_nr_slots(p); slot++) {
+		for (int slot = 0; slot < folioq_count(p); slot++) {
 			struct folio *folio = folioq_folio(p, slot);
 			if (!folio)
 				continue;

fs/netfs/write_issue.c

@@ -508,6 +508,30 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 	return 0;
 }
 
+/*
+ * End the issuing of writes, letting the collector know we're done.
+ */
+static void netfs_end_issue_write(struct netfs_io_request *wreq)
+{
+	bool needs_poke = true;
+
+	smp_wmb(); /* Write subreq lists before ALL_QUEUED. */
+	set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
+
+	for (int s = 0; s < NR_IO_STREAMS; s++) {
+		struct netfs_io_stream *stream = &wreq->io_streams[s];
+
+		if (!stream->active)
+			continue;
+		if (!list_empty(&stream->subrequests))
+			needs_poke = false;
+		netfs_issue_write(wreq, stream);
+	}
+
+	if (needs_poke)
+		netfs_wake_write_collector(wreq, false);
+}
+
 /*
  * Write some of the pending data back to the server
  */
@@ -559,10 +583,7 @@ int netfs_writepages(struct address_space *mapping,
 			break;
 	} while ((folio = writeback_iter(mapping, wbc, folio, &error)));
 
-	for (int s = 0; s < NR_IO_STREAMS; s++)
-		netfs_issue_write(wreq, &wreq->io_streams[s]);
-	smp_wmb(); /* Write lists before ALL_QUEUED. */
-	set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
+	netfs_end_issue_write(wreq);
 
 	mutex_unlock(&ictx->wb_lock);
 
@@ -650,10 +671,7 @@ int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_contr
 	if (writethrough_cache)
 		netfs_write_folio(wreq, wbc, writethrough_cache);
 
-	netfs_issue_write(wreq, &wreq->io_streams[0]);
-	netfs_issue_write(wreq, &wreq->io_streams[1]);
-	smp_wmb(); /* Write lists before ALL_QUEUED. */
-	set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
+	netfs_end_issue_write(wreq);
 
 	mutex_unlock(&ictx->wb_lock);
 
@@ -699,13 +717,7 @@ int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t
 			break;
 	}
 
-	netfs_issue_write(wreq, upload);
-
-	smp_wmb(); /* Write lists before ALL_QUEUED. */
-	set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
-	if (list_empty(&upload->subrequests))
-		netfs_wake_write_collector(wreq, false);
-
+	netfs_end_issue_write(wreq);
 	_leave(" = %d", error);
 	return error;
 }

include/linux/folio_queue.h

@@ -81,7 +81,7 @@ static inline unsigned int folioq_count(struct folio_queue *folioq)
 }
 
 /**
- * folioq_count: Query if a folio queue segment is full
+ * folioq_full: Query if a folio queue segment is full
  * @folioq: The segment to query
  *
  * Query if a folio queue segment is fully occupied.  Note that this does not

lib/iov_iter.c

@@ -1033,7 +1033,7 @@ static ssize_t iter_folioq_get_pages(struct iov_iter *iter,
 		if (maxpages == 0 || extracted >= maxsize)
 			break;
 
-		if (offset >= fsize) {
+		if (iov_offset >= fsize) {
 			iov_offset = 0;
 			slot++;
 			if (slot == folioq_nr_slots(folioq) && folioq->next) {