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iomap: Allow filesystem to call iomap_dio_complete without i_rwsem

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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>
This commit is contained in:
Christoph Hellwig
2020-09-28 08:51:08 -07:00
committed by Darrick J. Wong
parent 4595a298d5
commit c3d4ed1abe
2 changed files with 31 additions and 9 deletions
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5
include/linux/iomap.h
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@@ -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