Merge tag 'iomap-6.3-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull iomap updates from Darrick Wong:
 "This is mostly rearranging things to make life easier for gfs2,
  nothing all that mindblowing for this release.

   - Change when the iomap page_done function is called so that we still
     have a locked folio in the success case. This fixes a writeback
     race in gfs2

   - Change when the iomap page_prepare function is called so that gfs2
     can recover from OOM scenarios more gracefully

   - Rename the iomap page_ops to folio_ops, since they operate on
     folios now"

* tag 'iomap-6.3-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  iomap: Rename page_ops to folio_ops
  iomap: Rename page_prepare handler to get_folio
  iomap: Add __iomap_get_folio helper
  iomap/gfs2: Get page in page_prepare handler
  iomap: Add iomap_get_folio helper
  iomap: Rename page_done handler to put_folio
  iomap/gfs2: Unlock and put folio in page_done handler
  iomap: Add __iomap_put_folio helper

Author: torvalds

fs/gfs2/bmap.c

@@ -956,36 +956,50 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
 	goto out;
 }
 
-static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos,
-				   unsigned len)
+static struct folio *
+gfs2_iomap_get_folio(struct iomap_iter *iter, loff_t pos, unsigned len)
 {
+	struct inode *inode = iter->inode;
 	unsigned int blockmask = i_blocksize(inode) - 1;
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
 	unsigned int blocks;
+	struct folio *folio;
+	int status;
 
 	blocks = ((pos & blockmask) + len + blockmask) >> inode->i_blkbits;
-	return gfs2_trans_begin(sdp, RES_DINODE + blocks, 0);
+	status = gfs2_trans_begin(sdp, RES_DINODE + blocks, 0);
+	if (status)
+		return ERR_PTR(status);
+
+	folio = iomap_get_folio(iter, pos);
+	if (IS_ERR(folio))
+		gfs2_trans_end(sdp);
+	return folio;
 }
 
-static void gfs2_iomap_page_done(struct inode *inode, loff_t pos,
-				 unsigned copied, struct page *page)
+static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos,
+				 unsigned copied, struct folio *folio)
 {
 	struct gfs2_trans *tr = current->journal_info;
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
 
-	if (page && !gfs2_is_stuffed(ip))
-		gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied);
+	if (!gfs2_is_stuffed(ip))
+		gfs2_page_add_databufs(ip, &folio->page, offset_in_page(pos),
+				       copied);
+
+	folio_unlock(folio);
+	folio_put(folio);
 
 	if (tr->tr_num_buf_new)
 		__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 
 	gfs2_trans_end(sdp);
 }
 
-static const struct iomap_page_ops gfs2_iomap_page_ops = {
-	.page_prepare = gfs2_iomap_page_prepare,
-	.page_done = gfs2_iomap_page_done,
+static const struct iomap_folio_ops gfs2_iomap_folio_ops = {
+	.get_folio = gfs2_iomap_get_folio,
+	.put_folio = gfs2_iomap_put_folio,
 };
 
 static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
@@ -1061,7 +1075,7 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 	}
 
 	if (gfs2_is_stuffed(ip) || gfs2_is_jdata(ip))
-		iomap->page_ops = &gfs2_iomap_page_ops;
+		iomap->folio_ops = &gfs2_iomap_folio_ops;
 	return 0;
 
 out_trans_end:
@@ -1277,7 +1291,7 @@ int gfs2_alloc_extent(struct inode *inode, u64 lblock, u64 *dblock,
 /*
  * NOTE: Never call gfs2_block_zero_range with an open transaction because it
  * uses iomap write to perform its actions, which begin their own transactions
- * (iomap_begin, page_prepare, etc.)
+ * (iomap_begin, get_folio, etc.)
  */
 static int gfs2_block_zero_range(struct inode *inode, loff_t from,
 				 unsigned int length)

fs/iomap/buffered-io.c

@@ -457,6 +457,33 @@ bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
 }
 EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
 
+/**
+ * iomap_get_folio - get a folio reference for writing
+ * @iter: iteration structure
+ * @pos: start offset of write
+ *
+ * Returns a locked reference to the folio at @pos, or an error pointer if the
+ * folio could not be obtained.
+ */
+struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos)
+{
+	unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
+	struct folio *folio;
+
+	if (iter->flags & IOMAP_NOWAIT)
+		fgp |= FGP_NOWAIT;
+
+	folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
+			fgp, mapping_gfp_mask(iter->inode->i_mapping));
+	if (folio)
+		return folio;
+
+	if (iter->flags & IOMAP_NOWAIT)
+		return ERR_PTR(-EAGAIN);
+	return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(iomap_get_folio);
+
 bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags)
 {
 	trace_iomap_release_folio(folio->mapping->host, folio_pos(folio),
@@ -575,6 +602,30 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
 	return 0;
 }
 
+static struct folio *__iomap_get_folio(struct iomap_iter *iter, loff_t pos,
+		size_t len)
+{
+	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
+
+	if (folio_ops && folio_ops->get_folio)
+		return folio_ops->get_folio(iter, pos, len);
+	else
+		return iomap_get_folio(iter, pos);
+}
+
+static void __iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret,
+		struct folio *folio)
+{
+	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
+
+	if (folio_ops && folio_ops->put_folio) {
+		folio_ops->put_folio(iter->inode, pos, ret, folio);
+	} else {
+		folio_unlock(folio);
+		folio_put(folio);
+	}
+}
+
 static int iomap_write_begin_inline(const struct iomap_iter *iter,
 		struct folio *folio)
 {
@@ -587,15 +638,11 @@ static int iomap_write_begin_inline(const struct iomap_iter *iter,
 static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
 		size_t len, struct folio **foliop)
 {
-	const struct iomap_page_ops *page_ops = iter->iomap.page_ops;
+	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 	struct folio *folio;
-	unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
 	int status = 0;
 
-	if (iter->flags & IOMAP_NOWAIT)
-		fgp |= FGP_NOWAIT;
-
 	BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
 	if (srcmap != &iter->iomap)
 		BUG_ON(pos + len > srcmap->offset + srcmap->length);
@@ -606,18 +653,9 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
 	if (!mapping_large_folio_support(iter->inode->i_mapping))
 		len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
 
-	if (page_ops && page_ops->page_prepare) {
-		status = page_ops->page_prepare(iter->inode, pos, len);
-		if (status)
-			return status;
-	}
-
-	folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
-			fgp, mapping_gfp_mask(iter->inode->i_mapping));
-	if (!folio) {
-		status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM;
-		goto out_no_page;
-	}
+	folio = __iomap_get_folio(iter, pos, len);
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
 
 	/*
 	 * Now we have a locked folio, before we do anything with it we need to
@@ -629,9 +667,9 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
 	 * could do the wrong thing here (zero a page range incorrectly or fail
 	 * to zero) and corrupt data.
 	 */
-	if (page_ops && page_ops->iomap_valid) {
-		bool iomap_valid = page_ops->iomap_valid(iter->inode,
-							&iter->iomap);
+	if (folio_ops && folio_ops->iomap_valid) {
+		bool iomap_valid = folio_ops->iomap_valid(iter->inode,
+							 &iter->iomap);
 		if (!iomap_valid) {
 			iter->iomap.flags |= IOMAP_F_STALE;
 			status = 0;
@@ -656,13 +694,9 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
 	return 0;
 
 out_unlock:
-	folio_unlock(folio);
-	folio_put(folio);
+	__iomap_put_folio(iter, pos, 0, folio);
 	iomap_write_failed(iter->inode, pos, len);
 
-out_no_page:
-	if (page_ops && page_ops->page_done)
-		page_ops->page_done(iter->inode, pos, 0, NULL);
 	return status;
 }
 
@@ -712,7 +746,6 @@ static size_t iomap_write_end_inline(const struct iomap_iter *iter,
 static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
 		size_t copied, struct folio *folio)
 {
-	const struct iomap_page_ops *page_ops = iter->iomap.page_ops;
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 	loff_t old_size = iter->inode->i_size;
 	size_t ret;
@@ -735,14 +768,10 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
 		i_size_write(iter->inode, pos + ret);
 		iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
 	}
-	folio_unlock(folio);
+	__iomap_put_folio(iter, pos, ret, folio);
 
 	if (old_size < pos)
 		pagecache_isize_extended(iter->inode, old_size, pos);
-	if (page_ops && page_ops->page_done)
-		page_ops->page_done(iter->inode, pos, ret, &folio->page);
-	folio_put(folio);
-
 	if (ret < len)
 		iomap_write_failed(iter->inode, pos + ret, len - ret);
 	return ret;

fs/xfs/xfs_iomap.c

@@ -83,7 +83,7 @@ xfs_iomap_valid(
 	return true;
 }
 
-static const struct iomap_page_ops xfs_iomap_page_ops = {
+static const struct iomap_folio_ops xfs_iomap_folio_ops = {
 	.iomap_valid		= xfs_iomap_valid,
 };
 
@@ -133,7 +133,7 @@ xfs_bmbt_to_iomap(
 		iomap->flags |= IOMAP_F_DIRTY;
 
 	iomap->validity_cookie = sequence_cookie;
-	iomap->page_ops = &xfs_iomap_page_ops;
+	iomap->folio_ops = &xfs_iomap_folio_ops;
 	return 0;
 }
 

include/linux/iomap.h

@@ -13,6 +13,7 @@
 struct address_space;
 struct fiemap_extent_info;
 struct inode;
+struct iomap_iter;
 struct iomap_dio;
 struct iomap_writepage_ctx;
 struct iov_iter;
@@ -84,7 +85,7 @@ struct vm_fault;
  */
 #define IOMAP_NULL_ADDR -1ULL	/* addr is not valid */
 
-struct iomap_page_ops;
+struct iomap_folio_ops;
 
 struct iomap {
 	u64			addr; /* disk offset of mapping, bytes */
@@ -96,7 +97,7 @@ struct iomap {
 	struct dax_device	*dax_dev; /* dax_dev for dax operations */
 	void			*inline_data;
 	void			*private; /* filesystem private */
-	const struct iomap_page_ops *page_ops;
+	const struct iomap_folio_ops *folio_ops;
 	u64			validity_cookie; /* used with .iomap_valid() */
 };
 
@@ -124,19 +125,20 @@ static inline bool iomap_inline_data_valid(const struct iomap *iomap)
 }
 
 /*
- * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare
- * and page_done will be called for each page written to.  This only applies to
- * buffered writes as unbuffered writes will not typically have pages
+ * When a filesystem sets folio_ops in an iomap mapping it returns, get_folio
+ * and put_folio will be called for each folio written to.  This only applies
+ * to buffered writes as unbuffered writes will not typically have folios
  * associated with them.
  *
- * When page_prepare succeeds, page_done will always be called to do any
- * cleanup work necessary.  In that page_done call, @page will be NULL if the
- * associated page could not be obtained.
+ * When get_folio succeeds, put_folio will always be called to do any
+ * cleanup work necessary.  put_folio is responsible for unlocking and putting
+ * @folio.
  */
-struct iomap_page_ops {
-	int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len);
-	void (*page_done)(struct inode *inode, loff_t pos, unsigned copied,
-			struct page *page);
+struct iomap_folio_ops {
+	struct folio *(*get_folio)(struct iomap_iter *iter, loff_t pos,
+			unsigned len);
+	void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied,
+			struct folio *folio);
 
 	/*
 	 * Check that the cached iomap still maps correctly to the filesystem's
@@ -259,6 +261,7 @@ int iomap_file_buffered_write_punch_delalloc(struct inode *inode,
 int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops);
 void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
 bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);
+struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos);
 bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
 void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
 int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,