linux-ext4 - [PATCH 05/19] fuse2fs: implement directio file reads

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Message-ID: <175573713820.21970.2115069375852971152.stgit@frogsfrogsfrogs>
Date: Wed, 20 Aug 2025 18:17:00 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: John@...ves.net, bernd@...ernd.com, linux-fsdevel@...r.kernel.org,
 linux-ext4@...r.kernel.org, miklos@...redi.hu, joannelkoong@...il.com,
 neal@...pa.dev
Subject: [PATCH 05/19] fuse2fs: implement directio file reads

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

Implement file reads via iomap.  Currently only directio is supported.

Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 misc/fuse2fs.c |   14 +++++++++++++-
 misc/fuse4fs.c |   14 +++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)


diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 8bf0fbcff093a7..1dda9c45cb5089 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -5359,7 +5359,19 @@ static int fuse2fs_iomap_begin_read(struct fuse2fs *ff, ext2_ino_t ino,
 				    uint64_t count, uint32_t opflags,
 				    struct fuse_file_iomap *read)
 {
-	return -ENOSYS;
+	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;
+
+	if (inode->i_flags & EXT4_EXTENTS_FL)
+		return fuse2fs_iomap_begin_extent(ff, ino, inode, pos, count,
+						  opflags, read);
+
+	return fuse2fs_iomap_begin_indirect(ff, ino, inode, pos, count,
+					    opflags, read);
 }
 
 static int fuse2fs_iomap_begin_write(struct fuse2fs *ff, ext2_ino_t ino,
diff --git a/misc/fuse4fs.c b/misc/fuse4fs.c
index 5debaf892b2113..2aa7ab646592e9 100644
--- a/misc/fuse4fs.c
+++ b/misc/fuse4fs.c
@@ -5767,7 +5767,19 @@ static int fuse4fs_iomap_begin_read(struct fuse4fs *ff, ext2_ino_t ino,
 				    uint64_t count, uint32_t opflags,
 				    struct fuse_file_iomap *read)
 {
-	return -ENOSYS;
+	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;
+
+	if (inode->i_flags & EXT4_EXTENTS_FL)
+		return fuse4fs_iomap_begin_extent(ff, ino, inode, pos, count,
+						  opflags, read);
+
+	return fuse4fs_iomap_begin_indirect(ff, ino, inode, pos, count,
+					    opflags, read);
 }
 
 static int fuse4fs_iomap_begin_write(struct fuse4fs *ff, ext2_ino_t ino,