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iomap: iomap_dio_rw() handles all sync writes 

Currently iomap_dio_rw() only handles (data)sync write completions
for AIO. This means we can't optimised non-AIO IO to minimise device
flushes as we can't tell the caller whether a flush is required or
not.

To solve this problem and enable further optimisations, make
iomap_dio_rw responsible for data sync behaviour for all IO, not
just AIO.

In doing so, the sync operation is now accounted as part of the DIO
IO by inode_dio_end(), hence post-IO data stability updates will no
long race against operations that serialise via inode_dio_wait()
such as truncate or hole punch.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Dave Chinner 2018-05-02 12:54:52 -07:00 committed by Darrick J. Wong
parent ed5c3e66a3
commit 4f8ff44ba0
2 changed files with 15 additions and 11 deletions
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21
fs/iomap.c
View File

@ -685,6 +685,7 @@ EXPORT_SYMBOL_GPL(iomap_seek_data);
* Private flags for iomap_dio, must not overlap with the public ones in
* iomap.h:
*/
#define IOMAP_DIO_NEED_SYNC (1 << 29)
#define IOMAP_DIO_WRITE (1 << 30)
#define IOMAP_DIO_DIRTY (1 << 31)
@ -759,6 +760,13 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
dio_warn_stale_pagecache(iocb->ki_filp);
}
/*
* If this is a DSYNC write, make sure we push it to stable storage now
* that we've written data.
*/
if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
ret = generic_write_sync(iocb, ret);
inode_dio_end(file_inode(iocb->ki_filp));
kfree(dio);
@ -769,13 +777,8 @@ static void iomap_dio_complete_work(struct work_struct *work)
{
struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
struct kiocb *iocb = dio->iocb;
bool is_write = (dio->flags & IOMAP_DIO_WRITE);
ssize_t ret;
ret = iomap_dio_complete(dio);
if (is_write && ret > 0)
ret = generic_write_sync(iocb, ret);
iocb->ki_complete(iocb, ret, 0);
iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);
}
/*
@ -961,6 +964,10 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
return copied;
}
/*
* iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
* is being issued as AIO or not.
*/
ssize_t
iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
@ -1006,6 +1013,8 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
dio->flags |= IOMAP_DIO_DIRTY;
} else {
dio->flags |= IOMAP_DIO_WRITE;
if (iocb->ki_flags & IOCB_DSYNC)
dio->flags |= IOMAP_DIO_NEED_SYNC;
flags |= IOMAP_WRITE;
}

5
fs/xfs/xfs_file.c
View File

@ -568,11 +568,6 @@ out:
* complete fully or fail.
*/
ASSERT(ret < 0 || ret == count);
if (ret > 0) {
/* Handle various SYNC-type writes */
ret = generic_write_sync(iocb, ret);
}
return ret;
}