linux-ext4 - [PATCH 09/16] fuse2fs: turn on iomap for pagecache IO

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Message-ID: <174787198595.1484996.5765521463651696077.stgit@frogsfrogsfrogs>
Date: Wed, 21 May 2025 17:13:11 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: John@...ves.net, linux-ext4@...r.kernel.org, miklos@...redi.hu,
 joannelkoong@...il.com, bernd@...ernd.com, linux-fsdevel@...r.kernel.org
Subject: [PATCH 09/16] fuse2fs: turn on iomap for pagecache IO

From: Darrick J. Wong <djwong@...nel.org>

Turn on iomap for pagecache IO to regular files.

Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 misc/fuse2fs.c |   64 ++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 57 insertions(+), 7 deletions(-)


diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index ec17f6203b4b70..7152979ed6694e 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1175,6 +1175,10 @@ static void *op_init(struct fuse_conn_info *conn
 	if (iomap_enabled(ff))
 		fuse_set_feature_flag(conn, FUSE_CAP_IOMAP_DIRECTIO);
 #endif
+#if defined(HAVE_FUSE_IOMAP) && defined(FUSE_CAP_IOMAP_PAGECACHE)
+	if (iomap_enabled(ff))
+		fuse_set_feature_flag(conn, FUSE_CAP_IOMAP_PAGECACHE);
+#endif
 
 	/* Clear the valid flag so that an unclean shutdown forces a fsck */
 	if (ff->writable) {
@@ -5017,9 +5021,6 @@ static int fuse_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
 {
 	errcode_t err;
 
-	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
-		return -ENOSYS;
-
 	/* fall back to slow path for inline data reads */
 	if (inode->i_flags & EXT4_INLINE_DATA_FL)
 		return -ENOSYS;
@@ -5099,9 +5100,6 @@ static int fuse_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,
 	errcode_t err;
 	int ret;
 
-	if (!(opflags & FUSE_IOMAP_OP_DIRECT))
-		return -ENOSYS;
-
 	if (pos >= max_size)
 		return -EFBIG;
 
@@ -5235,12 +5233,51 @@ static int op_iomap_begin(const char *path, uint64_t nodeid, uint64_t attr_ino,
 	return ret;
 }
 
+static int iomap_append_setsize(struct fuse2fs *ff, ext2_ino_t ino,
+				loff_t newsize)
+{
+	ext2_filsys fs = ff->fs;
+	struct ext2_inode_large inode;
+	ext2_off64_t isize;
+	errcode_t err;
+
+	dbg_printf(ff, "%s: ino=%u newsize=%llu\n", __func__, ino,
+		   (unsigned long long)newsize);
+
+	err = fuse2fs_read_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	isize = EXT2_I_SIZE(&inode);
+	if (newsize <= isize)
+		return 0;
+
+	dbg_printf(ff, "%s: ino=%u oldsize=%llu newsize=%llu\n", __func__, ino,
+		   (unsigned long long)isize,
+		   (unsigned long long)newsize);
+
+	/*
+	 * XXX cheesily update the ondisk size even though we only want to do
+	 * the incore size until writeback happens
+	 */
+	err = ext2fs_inode_size_set(fs, EXT2_INODE(&inode), newsize);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	err = fuse2fs_write_inode(fs, ino, &inode);
+	if (err)
+		return translate_error(fs, ino, err);
+
+	return 0;
+}
+
 static int op_iomap_end(const char *path, uint64_t nodeid, uint64_t attr_ino,
 			off_t pos, uint64_t count, uint32_t opflags,
 			ssize_t written, const struct fuse_iomap *iomap)
 {
 	struct fuse_context *ctxt = fuse_get_context();
 	struct fuse2fs *ff = (struct fuse2fs *)ctxt->private_data;
+	int ret = 0;
 
 	FUSE2FS_CHECK_CONTEXT(ff);
 
@@ -5255,9 +5292,22 @@ static int op_iomap_end(const char *path, uint64_t nodeid, uint64_t attr_ino,
 		   opflags,
 		   written,
 		   iomap->flags);
+
+	if ((opflags & FUSE_IOMAP_OP_WRITE) &&
+	    !(opflags & FUSE_IOMAP_OP_DIRECT) &&
+	    (iomap->flags & FUSE_IOMAP_F_SIZE_CHANGED) &&
+	    written > 0) {
+		ret = iomap_append_setsize(ff, attr_ino, pos + written);
+		if (ret)
+			goto out_unlock;
+	}
+
+out_unlock:
+	if (ret < 0)
+		dbg_printf(ff, "%s: libfuse ret=%d\n", __func__, ret);
 	pthread_mutex_unlock(&ff->bfl);
 
-	return 0;
+	return ret;
 }
 
 static inline bool can_merge_mappings(const struct ext2fs_extent *left,