Commit 57e1176e authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

fuse: implement read/write passthrough 



Use the backing file read/write helpers to implement read/write
passthrough to a backing file.

After read/write, we invalidate a/c/mtime/size attributes.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 4a90451b

fs/fuse/file.c

+12 −6
Original line number Diff line number Diff line
@@ -1693,10 +1693,13 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	if (FUSE_IS_DAX(inode))

		return fuse_dax_read_iter(iocb, to);



	if (!(ff->open_flags & FOPEN_DIRECT_IO))

		return fuse_cache_read_iter(iocb, to);

	else

	/* FOPEN_DIRECT_IO overrides FOPEN_PASSTHROUGH */

	if (ff->open_flags & FOPEN_DIRECT_IO)

		return fuse_direct_read_iter(iocb, to);

	else if (fuse_file_passthrough(ff))

		return fuse_passthrough_read_iter(iocb, to);

	else

		return fuse_cache_read_iter(iocb, to);

}



static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
@@ -1711,10 +1714,13 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	if (FUSE_IS_DAX(inode))

		return fuse_dax_write_iter(iocb, from);



	if (!(ff->open_flags & FOPEN_DIRECT_IO))

		return fuse_cache_write_iter(iocb, from);

	else

	/* FOPEN_DIRECT_IO overrides FOPEN_PASSTHROUGH */

	if (ff->open_flags & FOPEN_DIRECT_IO)

		return fuse_direct_write_iter(iocb, from);

	else if (fuse_file_passthrough(ff))

		return fuse_passthrough_write_iter(iocb, from);

	else

		return fuse_cache_write_iter(iocb, from);

}



static void fuse_writepage_free(struct fuse_writepage_args *wpa)

fs/fuse/fuse_i.h

+3 −0
Original line number Diff line number Diff line
@@ -1466,4 +1466,7 @@ static inline struct file *fuse_file_passthrough(struct fuse_file *ff) 
#endif

}



ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter);

ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *iter);



#endif /* _FS_FUSE_I_H */

fs/fuse/passthrough.c

+69 −0
Original line number Diff line number Diff line
@@ -10,6 +10,75 @@ 
#include <linux/file.h>

#include <linux/backing-file.h>



static void fuse_file_accessed(struct file *file)

{

	struct inode *inode = file_inode(file);



	fuse_invalidate_atime(inode);

}



static void fuse_file_modified(struct file *file)

{

	struct inode *inode = file_inode(file);



	fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE);

}



ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter)

{

	struct file *file = iocb->ki_filp;

	struct fuse_file *ff = file->private_data;

	struct file *backing_file = fuse_file_passthrough(ff);

	size_t count = iov_iter_count(iter);

	ssize_t ret;

	struct backing_file_ctx ctx = {

		.cred = ff->cred,

		.user_file = file,

		.accessed = fuse_file_accessed,

	};





	pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu\n", __func__,

		 backing_file, iocb->ki_pos, count);



	if (!count)

		return 0;



	ret = backing_file_read_iter(backing_file, iter, iocb, iocb->ki_flags,

				     &ctx);



	return ret;

}



ssize_t fuse_passthrough_write_iter(struct kiocb *iocb,

				    struct iov_iter *iter)

{

	struct file *file = iocb->ki_filp;

	struct inode *inode = file_inode(file);

	struct fuse_file *ff = file->private_data;

	struct file *backing_file = fuse_file_passthrough(ff);

	size_t count = iov_iter_count(iter);

	ssize_t ret;

	struct backing_file_ctx ctx = {

		.cred = ff->cred,

		.user_file = file,

		.end_write = fuse_file_modified,

	};



	pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu\n", __func__,

		 backing_file, iocb->ki_pos, count);



	if (!count)

		return 0;



	inode_lock(inode);

	ret = backing_file_write_iter(backing_file, iter, iocb, iocb->ki_flags,

				      &ctx);

	inode_unlock(inode);



	return ret;

}



struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)

{

	if (fb && refcount_inc_not_zero(&fb->count))