[PATCH v11 02/14] fs: export variant of generic_write_checks without iov_iter
From: Omar Sandoval <osandov@osandov.com>
Date: 2021-09-01 17:01:33
Also in:
linux-btrfs, linux-fsdevel
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
From: Omar Sandoval <redacted> 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. Signed-off-by: Omar Sandoval <redacted> --- fs/read_write.c | 33 ++++++++++++++++++++------------- include/linux/fs.h | 1 + 2 files changed, 21 insertions(+), 13 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 0029ff2b0ca8..46b3dcff3b24 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c@@ -1633,24 +1633,16 @@ 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 */
@@ -1660,8 +1652,23 @@ 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;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0de4d75339b9..3a2ff5306236 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -3227,6 +3227,7 @@ 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 *); +extern 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);
--
2.33.0