[PATCH 6.17 339/371] ext4: fail unaligned direct IO write with EINVAL
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2025-10-17 15:45:10
Also in:
linux-patches
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
6.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jan Kara <jack@suse.cz>
commit 963845748fe67125006859229487b45485564db7 upstream.
Commit bc264fea0f6f ("iomap: support incremental iomap_iter advances")
changed the error handling logic in iomap_iter(). Previously any error
from iomap_dio_bio_iter() got propagated to userspace, after this commit
if ->iomap_end returns error, it gets propagated to userspace instead of
an error from iomap_dio_bio_iter(). This results in unaligned writes to
ext4 to silently fallback to buffered IO instead of erroring out.
Now returning ENOTBLK for DIO writes from ext4_iomap_end() seems
unnecessary these days. It is enough to return ENOTBLK from
ext4_iomap_begin() when we don't support DIO write for that particular
file offset (due to hole).
Fixes: bc264fea0f6f ("iomap: support incremental iomap_iter advances")
Cc: stable@kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Message-ID: [off-list ref]
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/inode.c | 35 -----------------------------------
1 file changed, 35 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5b7a15db4953..c3b23c90fd11 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c@@ -3872,47 +3872,12 @@ static int ext4_iomap_overwrite_begin(struct inode *inode, loff_t offset, return ret; } -static inline bool ext4_want_directio_fallback(unsigned flags, ssize_t written) -{ - /* must be a directio to fall back to buffered */ - if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != - (IOMAP_WRITE | IOMAP_DIRECT)) - return false; - - /* atomic writes are all-or-nothing */ - if (flags & IOMAP_ATOMIC) - return false; - - /* can only try again if we wrote nothing */ - return written == 0; -} - -static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length, - ssize_t written, unsigned flags, struct iomap *iomap) -{ - /* - * Check to see whether an error occurred while writing out the data to - * the allocated blocks. If so, return the magic error code for - * non-atomic write so that we fallback to buffered I/O and attempt to - * complete the remainder of the I/O. - * For non-atomic writes, any blocks that may have been - * allocated in preparation for the direct I/O will be reused during - * buffered I/O. For atomic write, we never fallback to buffered-io. - */ - if (ext4_want_directio_fallback(flags, written)) - return -ENOTBLK; - - return 0; -} - const struct iomap_ops ext4_iomap_ops = { .iomap_begin = ext4_iomap_begin, - .iomap_end = ext4_iomap_end, }; const struct iomap_ops ext4_iomap_overwrite_ops = { .iomap_begin = ext4_iomap_overwrite_begin, - .iomap_end = ext4_iomap_end, }; static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
--
2.51.0