From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-fsdevel@vger.kernel.org
Cc: hch@infradead.org, willy@infradead.org,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH v3] Return bytes transferred for partial direct I/O
Date: Fri, 29 Sep 2017 10:50:30 -0500 [thread overview]
Message-ID: <20170929155030.7726-1-rgoldwyn@suse.de> (raw)
In case direct I/O encounters an error midway, it returns the error.
Instead it should be returning the number of bytes transferred so far.
Test case for filesystems (with ENOSPC):
1. Create an almost full filesystem
2. Create a file, say /mnt/lastfile, until the filesystem is full.
3. Direct write() with count > sizeof /mnt/lastfile.
Result: write() returns -ENOSPC. However, file content has data written
in step 3.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Changes since v1:
- incorporated iomap and block devices
Changes since v2:
- realized that file size was not increasing when performing a (partial)
direct I/O because end_io function was receiving the error instead of
size in iomap's dio end io. Fixed.
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 93d088ffc05c..1c6640ffb929 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -421,7 +421,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
if (!ret)
ret = blk_status_to_errno(dio->bio.bi_status);
- if (likely(!ret))
+ if (likely(dio->size))
ret = dio->size;
bio_put(&dio->bio);
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 5fa2211e49ae..0fc1789498ae 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -255,8 +255,6 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, bool is_async)
ret = dio->page_errors;
if (ret == 0)
ret = dio->io_error;
- if (ret == 0)
- ret = transferred;
if (dio->end_io) {
int err;
@@ -284,7 +282,7 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, bool is_async)
}
kmem_cache_free(dio_cache, dio);
- return ret;
+ return transferred ? transferred : ret;
}
static void dio_aio_complete_work(struct work_struct *work)
diff --git a/fs/iomap.c b/fs/iomap.c
index 269b24a01f32..019c4d993300 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -714,28 +714,29 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
{
struct kiocb *iocb = dio->iocb;
ssize_t ret;
+ ssize_t transferred = 0;
if (dio->end_io) {
ret = dio->end_io(iocb,
- dio->error ? dio->error : dio->size,
+ dio->size ? dio->size : dio->error,
dio->flags);
} else {
ret = dio->error;
}
- if (likely(!ret)) {
- ret = dio->size;
+ if (likely(dio->size)) {
+ transferred = dio->size;
/* check for short read */
- if (iocb->ki_pos + ret > dio->i_size &&
+ if (iocb->ki_pos + transferred > dio->i_size &&
!(dio->flags & IOMAP_DIO_WRITE))
- ret = dio->i_size - iocb->ki_pos;
- iocb->ki_pos += ret;
+ transferred = dio->i_size - iocb->ki_pos;
+ iocb->ki_pos += transferred;
}
inode_dio_end(file_inode(iocb->ki_filp));
kfree(dio);
- return ret;
+ return transferred ? transferred : ret;
}
static void iomap_dio_complete_work(struct work_struct *work)
next reply other threads:[~2017-09-29 15:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-29 15:50 Goldwyn Rodrigues [this message]
2017-10-01 8:22 ` [PATCH v3] Return bytes transferred for partial direct I/O Christoph Hellwig
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