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fs: export variant of generic_write_checks without iov_iter

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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: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Omar Sandoval 2021-08-12 15:34:57 -07:00 committed by David Sterba
parent 871129332d
commit f6f7a25a65
2 changed files with 21 additions and 13 deletions
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33
fs/read_write.c
View File

@ -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;

1
include/linux/fs.h
View File

@ -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);