* @pos: beginning offset in pages to write
* @count: number of bytes to write
*
- * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
+ * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
* as it forces O_SYNC writers to different parts of the same file
* to be serialised right until io completion.
*/
}
EXPORT_SYMBOL(find_get_page);
-/**
- * find_trylock_page - find and lock a page
- * @mapping: the address_space to search
- * @offset: the page index
- *
- * Same as find_get_page(), but trylock it instead of incrementing the count.
- */
-struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
-{
- struct page *page;
-
- read_lock_irq(&mapping->tree_lock);
- page = radix_tree_lookup(&mapping->page_tree, offset);
- if (page && TestSetPageLocked(page))
- page = NULL;
- read_unlock_irq(&mapping->tree_lock);
- return page;
-}
-EXPORT_SYMBOL(find_trylock_page);
-
/**
* find_lock_page - locate, pin and lock a pagecache page
* @mapping: the address_space to search
* @mapping: target address_space
* @index: the page index
*
- * Same as grab_cache_page, but do not wait if the page is unavailable.
+ * Same as grab_cache_page(), but do not wait if the page is unavailable.
* This is intended for speculative data generators, where the data can
* be regenerated if the page couldn't be grabbed. This routine should
* be safe to call while holding the lock for another page.
/* Limit the size of the copy to the caller's write size */
bytes = min(bytes, count);
- /*
- * Limit the size of the copy to that of the current segment,
- * because fault_in_pages_readable() doesn't know how to walk
- * segments.
- */
- bytes = min(bytes, cur_iov->iov_len - iov_base);
-
- /*
- * Bring in the user page that we will copy from _first_.
- * Otherwise there's a nasty deadlock on copying from the
- * same page as we're writing to, without it being marked
- * up-to-date.
+ /* We only need to worry about prefaulting when writes are from
+ * user-space. NFSd uses vfs_writev with several non-aligned
+ * segments in the vector, and limiting to one segment a time is
+ * a noticeable performance for re-write
*/
- fault_in_pages_readable(buf, bytes);
+ if (!segment_eq(get_fs(), KERNEL_DS)) {
+ /*
+ * Limit the size of the copy to that of the current
+ * segment, because fault_in_pages_readable() doesn't
+ * know how to walk segments.
+ */
+ bytes = min(bytes, cur_iov->iov_len - iov_base);
+ /*
+ * Bring in the user page that we will copy from
+ * _first_. Otherwise there's a nasty deadlock on
+ * copying from the same page as we're writing to,
+ * without it being marked up-to-date.
+ */
+ fault_in_pages_readable(buf, bytes);
+ }
page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
if (!page) {
status = -ENOMEM;
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
ssize_t retval;
- size_t write_len = 0;
+ size_t write_len;
+ pgoff_t end = 0; /* silence gcc */
/*
* If it's a write, unmap all mmappings of the file up-front. This
*/
if (rw == WRITE) {
write_len = iov_length(iov, nr_segs);
+ end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
if (mapping_mapped(mapping))
unmap_mapping_range(mapping, offset, write_len, 0);
}
retval = filemap_write_and_wait(mapping);
- if (retval == 0) {
- retval = mapping->a_ops->direct_IO(rw, iocb, iov,
- offset, nr_segs);
- if (rw == WRITE && mapping->nrpages) {
- pgoff_t end = (offset + write_len - 1)
- >> PAGE_CACHE_SHIFT;
- int err = invalidate_inode_pages2_range(mapping,
+ if (retval)
+ goto out;
+
+ /*
+ * After a write we want buffered reads to be sure to go to disk to get
+ * the new data. We invalidate clean cached page from the region we're
+ * about to write. We do this *before* the write so that we can return
+ * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
+ */
+ if (rw == WRITE && mapping->nrpages) {
+ retval = invalidate_inode_pages2_range(mapping,
offset >> PAGE_CACHE_SHIFT, end);
- if (err)
- retval = err;
- }
+ if (retval)
+ goto out;
}
+
+ retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
+ if (retval)
+ goto out;
+
+ /*
+ * Finally, try again to invalidate clean pages which might have been
+ * faulted in by get_user_pages() if the source of the write was an
+ * mmap()ed region of the file we're writing. That's a pretty crazy
+ * thing to do, so we don't support it 100%. If this invalidation
+ * fails and we have -EIOCBQUEUED we ignore the failure.
+ */
+ if (rw == WRITE && mapping->nrpages) {
+ int err = invalidate_inode_pages2_range(mapping,
+ offset >> PAGE_CACHE_SHIFT, end);
+ if (err && retval >= 0)
+ retval = err;
+ }
+out:
return retval;
}
projects / powerpc.git / blobdiff