diff options
| -rw-r--r-- | fs/libfs.c | 35 | ||||
| -rw-r--r-- | include/linux/fs.h | 2 |
2 files changed, 37 insertions, 0 deletions
diff --git a/fs/libfs.c b/fs/libfs.c index ea9a6cc9b35..232bea425b0 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -547,6 +547,40 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, } /** + * simple_write_to_buffer - copy data from user space to the buffer + * @to: the buffer to write to + * @available: the size of the buffer + * @ppos: the current position in the buffer + * @from: the user space buffer to read from + * @count: the maximum number of bytes to read + * + * The simple_write_to_buffer() function reads up to @count bytes from the user + * space address starting at @from into the buffer @to at offset @ppos. + * + * On success, the number of bytes written is returned and the offset @ppos is + * advanced by this number, or negative value is returned on error. + **/ +ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, + const void __user *from, size_t count) +{ + loff_t pos = *ppos; + size_t res; + + if (pos < 0) + return -EINVAL; + if (pos >= available || !count) + return 0; + if (count > available - pos) + count = available - pos; + res = copy_from_user(to + pos, from, count); + if (res == count) + return -EFAULT; + count -= res; + *ppos = pos + count; + return count; +} + +/** * memory_read_from_buffer - copy data from the buffer * @to: the kernel space buffer to read to * @count: the maximum number of bytes to read @@ -864,6 +898,7 @@ EXPORT_SYMBOL(simple_statfs); EXPORT_SYMBOL(simple_sync_file); EXPORT_SYMBOL(simple_unlink); EXPORT_SYMBOL(simple_read_from_buffer); +EXPORT_SYMBOL(simple_write_to_buffer); EXPORT_SYMBOL(memory_read_from_buffer); EXPORT_SYMBOL(simple_transaction_set); EXPORT_SYMBOL(simple_transaction_get); diff --git a/include/linux/fs.h b/include/linux/fs.h index 44f35aea2f1..948bd2bfb1d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2362,6 +2362,8 @@ extern void simple_release_fs(struct vfsmount **mount, int *count); extern ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, const void *from, size_t available); +extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, + const void __user *from, size_t count); extern int simple_fsync(struct file *, struct dentry *, int); |