From: Christoph Hellwig <hch@lst.de>
To: Josef Bacik <josef@toxicpanda.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>,
David Sterba <dsterba@suse.com>,
"linux-btrfs @ vger . kernel . org" <linux-btrfs@vger.kernel.org>,
Filipe Manana <fdmanana@gmail.com>,
Christoph Hellwig <hch@lst.de>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: [RFC PATCH] btrfs: don't call btrfs_sync_file from iomap context
Date: Thu, 3 Sep 2020 18:32:36 +0200 [thread overview]
Message-ID: <20200903163236.GA26043@lst.de> (raw)
In-Reply-To: <42efa646-73cd-d884-1c9c-dd889294bde2@toxicpanda.com>
We could trivially do something like this to allow the file system
to call iomap_dio_complete without i_rwsem:
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index c1aafb2ab99072..d970c6bbbe115d 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -76,7 +76,7 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
dio->submit.cookie = submit_bio(bio);
}
-static ssize_t iomap_dio_complete(struct iomap_dio *dio)
+ssize_t iomap_dio_complete(struct iomap_dio *dio)
{
const struct iomap_dio_ops *dops = dio->dops;
struct kiocb *iocb = dio->iocb;
@@ -130,6 +130,7 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
return ret;
}
+EXPORT_SYMBOL_GPL(iomap_dio_complete);
static void iomap_dio_complete_work(struct work_struct *work)
{
@@ -406,8 +407,8 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
* Returns -ENOTBLK In case of a page invalidation invalidation failure for
* writes. The callers needs to fall back to buffered I/O in this case.
*/
-ssize_t
-iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+struct iomap_dio *
+__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
bool wait_for_completion)
{
@@ -421,14 +422,14 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
struct iomap_dio *dio;
if (!count)
- return 0;
+ return NULL;
if (WARN_ON(is_sync_kiocb(iocb) && !wait_for_completion))
- return -EIO;
+ return ERR_PTR(-EIO);
dio = kmalloc(sizeof(*dio), GFP_KERNEL);
if (!dio)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
dio->iocb = iocb;
atomic_set(&dio->ref, 1);
@@ -558,7 +559,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
dio->wait_for_completion = wait_for_completion;
if (!atomic_dec_and_test(&dio->ref)) {
if (!wait_for_completion)
- return -EIOCBQUEUED;
+ return ERR_PTR(-EIOCBQUEUED);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
@@ -574,10 +575,25 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
__set_current_state(TASK_RUNNING);
}
- return iomap_dio_complete(dio);
+ return dio;
out_free_dio:
kfree(dio);
- return ret;
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(__iomap_dio_rw);
+
+ssize_t
+iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+ const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
+ bool wait_for_completion)
+{
+ struct iomap_dio *dio;
+
+ dio = __iomap_dio_rw(iocb, iter, ops, dops, wait_for_completion);
+ if (IS_ERR_OR_NULL(dio))
+ return PTR_ERR_OR_ZERO(dio);
+ return iomap_dio_complete(dio);
}
EXPORT_SYMBOL_GPL(iomap_dio_rw);
+
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 4d1d3c3469e9a4..172b3397a1a371 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -13,6 +13,7 @@
struct address_space;
struct fiemap_extent_info;
struct inode;
+struct iomap_dio;
struct iomap_writepage_ctx;
struct iov_iter;
struct kiocb;
@@ -258,6 +259,10 @@ struct iomap_dio_ops {
ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
bool wait_for_completion);
+struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+ const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
+ bool wait_for_completion);
+ssize_t iomap_dio_complete(struct iomap_dio *dio);
int iomap_dio_iopoll(struct kiocb *kiocb, bool spin);
#ifdef CONFIG_SWAP
next prev parent reply other threads:[~2020-09-03 16:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200901130644.12655-1-johannes.thumshirn@wdc.com>
2020-09-01 15:11 ` [RFC PATCH] btrfs: don't call btrfs_sync_file from iomap context Josef Bacik
2020-09-01 17:45 ` Darrick J. Wong
2020-09-01 17:55 ` Josef Bacik
2020-09-01 21:46 ` Dave Chinner
2020-09-01 22:19 ` Josef Bacik
2020-09-01 23:58 ` Dave Chinner
2020-09-02 0:22 ` Josef Bacik
2020-09-02 7:12 ` Johannes Thumshirn
2020-09-02 11:10 ` Josef Bacik
2020-09-02 16:29 ` Darrick J. Wong
2020-09-02 16:47 ` Josef Bacik
2020-09-02 11:44 ` Matthew Wilcox
2020-09-02 12:20 ` Dave Chinner
2020-09-02 12:42 ` Josef Bacik
2020-09-03 2:28 ` Dave Chinner
2020-09-03 9:49 ` Filipe Manana
2020-09-03 16:32 ` Christoph Hellwig [this message]
2020-09-03 16:46 ` Josef Bacik
2020-09-07 0:04 ` Dave Chinner
2020-09-15 21:48 ` Goldwyn Rodrigues
2020-09-17 3:09 ` Dave Chinner
2020-09-17 5:52 ` Christoph Hellwig
2020-09-17 6:29 ` Dave Chinner
2020-09-17 6:42 ` Christoph Hellwig
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