Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c93b8af0 authored by Nikhilesh Reddy's avatar Nikhilesh Reddy Committed by Gerrit - the friendly Code Review server
Browse files

fs:fuse: Disable shortcircuit when mmap is called on a file 



When some data is written to a file both mmap and regular io
there can be race conditions that can cause incorrect data
to be saved.

Disable shortcircuit on the specific files on which  mmap is called
until we add mmap support to shortcircuit.

Change-Id: Ic24219ab22d3130aa7e9e998a9e6798648a7321c
Signed-off-by: default avatarNikhilesh Reddy <reddyn@codeaurora.org>
parent e3ea6c56

fs/fuse/file.c

+12 −2
Original line number Diff line number Diff line
@@ -65,6 +65,9 @@ struct fuse_file *fuse_file_alloc(struct fuse_conn *fc) 
		return NULL;



	ff->rw_lower_file = NULL;

	ff->shortcircuit_enabled = 0;

	if (fc->shortcircuit_io)

		ff->shortcircuit_enabled = 1;

	ff->fc = fc;

	ff->reserved_req = fuse_request_alloc(0);

	if (unlikely(!ff->reserved_req)) {
@@ -1001,7 +1004,7 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
			return err;

	}



	if (ff && ff->rw_lower_file)

	if (ff && ff->shortcircuit_enabled && ff->rw_lower_file)

		ret_val = fuse_shortcircuit_read_iter(iocb, to);

	else

		ret_val = generic_file_read_iter(iocb, to);
@@ -1278,7 +1281,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	if (err)

		goto out;



	if (ff && ff->rw_lower_file) {

	if (ff && ff->shortcircuit_enabled && ff->rw_lower_file) {

		written = fuse_shortcircuit_write_iter(iocb, from);

		goto out;

	}
@@ -2173,6 +2176,9 @@ static const struct vm_operations_struct fuse_file_vm_ops = { 


static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)

{

	struct fuse_file *ff = file->private_data;



	ff->shortcircuit_enabled = 0;

	if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))

		fuse_link_write_file(file);
@@ -2183,6 +2189,10 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) 


static int fuse_direct_mmap(struct file *file, struct vm_area_struct *vma)

{

	struct fuse_file *ff = file->private_data;



	ff->shortcircuit_enabled = 0;



	/* Can't provide the coherency needed for MAP_SHARED */

	if (vma->vm_flags & VM_MAYSHARE)

		return -ENODEV;

fs/fuse/fuse_i.h

+1 −0
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ struct fuse_file { 


	/* the read write file */

	struct file *rw_lower_file;

	bool shortcircuit_enabled;

};



/** One input argument of a request */