pagecache_isize_extended — update pagecache after extension of i_size
void pagecache_isize_extended ( | struct inode * inode, |
| loff_t from, | |
loff_t to); |
struct inode * inodeinode for which i_size was extended
loff_t fromoriginal inode size
loff_t tonew inode size
Handle extension of inode size either caused by extending truncate or by
write starting after current i_size. We mark the page straddling current
i_size RO so that page_mkwrite is called on the nearest write access to
the page. This way filesystem can be sure that page_mkwrite is called on
the page before user writes to the page via mmap after the i_size has been
changed.
The function must be called after i_size is updated so that page fault coming after we unlock the page will already see the new i_size. The function must be called while we still hold i_mutex - this not only makes sure i_size is stable but also that userspace cannot observe new i_size value before we are prepared to store mmap writes at new inode size.