Commit f6f7a25a authored by Omar Sandoval's avatar Omar Sandoval Committed by David Sterba
Browse files

fs: export variant of generic_write_checks without iov_iter 



Encoded I/O in Btrfs needs to check a write with a given logical size
without an iov_iter that matches that size (because the iov_iter we have
is for the compressed data). So, factor out the parts of
generic_write_check() that don't need an iov_iter into a new
generic_write_checks_count() function and export that.

Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 87112933

fs/read_write.c

+20 −13
Original line number Diff line number Diff line
@@ -1618,24 +1618,16 @@ int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count) 
	return 0;

}



/*

 * Performs necessary checks before doing a write

 *

 * Can adjust writing position or amount of bytes to write.

 * Returns appropriate error code that caller should return or

 * zero in case that write should be allowed.

 */

ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)

/* Like generic_write_checks(), but takes size of write instead of iter. */

int generic_write_checks_count(struct kiocb *iocb, loff_t *count)

{

	struct file *file = iocb->ki_filp;

	struct inode *inode = file->f_mapping->host;

	loff_t count;

	int ret;



	if (IS_SWAPFILE(inode))

		return -ETXTBSY;



	if (!iov_iter_count(from))

	if (!*count)

		return 0;



	/* FIXME: this is for backwards compatibility with 2.4 */
@@ -1645,8 +1637,23 @@ ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) 
	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))

		return -EINVAL;



	count = iov_iter_count(from);

	ret = generic_write_check_limits(file, iocb->ki_pos, &count);

	return generic_write_check_limits(iocb->ki_filp, iocb->ki_pos, count);

}

EXPORT_SYMBOL(generic_write_checks_count);



/*

 * Performs necessary checks before doing a write

 *

 * Can adjust writing position or amount of bytes to write.

 * Returns appropriate error code that caller should return or

 * zero in case that write should be allowed.

 */

ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)

{

	loff_t count = iov_iter_count(from);

	int ret;



	ret = generic_write_checks_count(iocb, &count);

	if (ret)

		return ret;

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -3130,6 +3130,7 @@ extern int sb_min_blocksize(struct super_block *, int); 
extern int generic_file_mmap(struct file *, struct vm_area_struct *);

extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);

extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);

int generic_write_checks_count(struct kiocb *iocb, loff_t *count);

extern int generic_write_check_limits(struct file *file, loff_t pos,

		loff_t *count);

extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);