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authorChristoph Hellwig <hch@lst.de>2020-09-28 18:51:08 +0300
committerDarrick J. Wong <darrick.wong@oracle.com>2020-09-28 18:51:08 +0300
commitc3d4ed1abecfcfc801199cfadb71f5b80e025d9e (patch)
treee9c9f9b12f6161b19673284bfa80719a115d8b59 /fs/iomap
parent4595a298d5563cf76c1d852970f162051fd1a7a6 (diff)
downloadlinux-c3d4ed1abecfcfc801199cfadb71f5b80e025d9e.tar.xz
iomap: Allow filesystem to call iomap_dio_complete without i_rwsem
This is to avoid the deadlock caused in btrfs because of O_DIRECT | O_DSYNC. Filesystems such as btrfs require i_rwsem while performing sync on a file. iomap_dio_rw() is called under i_rw_sem. This leads to a deadlock because of: iomap_dio_complete() generic_write_sync() btrfs_sync_file() Separate out iomap_dio_complete() from iomap_dio_rw(), so filesystems can call iomap_dio_complete() after unlocking i_rwsem. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/iomap')
-rw-r--r--fs/iomap/direct-io.c35
1 files changed, 26 insertions, 9 deletions
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 024d4bb3028e..b005ef5f554e 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)
{
@@ -416,8 +417,8 @@ 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)
{
@@ -431,14 +432,14 @@ 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);
@@ -568,7 +569,7 @@ 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);
@@ -584,10 +585,26 @@ 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;
+ if (ret)
+ return ERR_PTR(ret);
+ return NULL;
+}
+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);