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ext4: fail unaligned direct IO write with EINVAL

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commit 963845748f upstream.

Commit bc264fea0f ("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: bc264fea0f ("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: <20250901112739.32484-2-jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara
2025-09-01 13:27:40 +02:00
committed by Greg Kroah-Hartman
parent d9774bbe39
commit e9663669a5
1 changed files with 0 additions and 35 deletions
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35
fs/ext4/inode.c
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@@ -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,