filemap.c (c7bad633e6b749b2d64e2421cc9d4ee0d1540a8a) filemap.c (41139aa4c3a31ee7e072fc63353c74035aade2ff)
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/filemap.c
4 *
5 * Copyright (C) 1994-1999 Linus Torvalds
6 */
7
8/*

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2548 IS_DAX(inode))
2549 return retval;
2550 }
2551
2552 return filemap_read(iocb, iter, retval);
2553}
2554EXPORT_SYMBOL(generic_file_read_iter);
2555
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/filemap.c
4 *
5 * Copyright (C) 1994-1999 Linus Torvalds
6 */
7
8/*

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2548 IS_DAX(inode))
2549 return retval;
2550 }
2551
2552 return filemap_read(iocb, iter, retval);
2553}
2554EXPORT_SYMBOL(generic_file_read_iter);
2555
2556static inline bool page_seek_match(struct page *page, bool seek_data)
2557{
2558 if (xa_is_value(page) || PageUptodate(page))
2559 return seek_data;
2560 return !seek_data;
2561}
2562
2563static inline
2564unsigned int seek_page_size(struct xa_state *xas, struct page *page)
2565{
2566 if (xa_is_value(page))
2567 return PAGE_SIZE << xa_get_order(xas->xa, xas->xa_index);
2568 return thp_size(page);
2569}
2570
2571/**
2572 * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache.
2573 * @mapping: Address space to search.
2574 * @start: First byte to consider.
2575 * @end: Limit of search (exclusive).
2576 * @whence: Either SEEK_HOLE or SEEK_DATA.
2577 *
2578 * If the page cache knows which blocks contain holes and which blocks
2579 * contain data, your filesystem can use this function to implement
2580 * SEEK_HOLE and SEEK_DATA. This is useful for filesystems which are
2581 * entirely memory-based such as tmpfs, and filesystems which support
2582 * unwritten extents.
2583 *
2584 * Return: The requested offset on successs, or -ENXIO if @whence specifies
2585 * SEEK_DATA and there is no data after @start. There is an implicit hole
2586 * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start
2587 * and @end contain data.
2588 */
2589loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
2590 loff_t end, int whence)
2591{
2592 XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT);
2593 pgoff_t max = (end - 1) / PAGE_SIZE;
2594 bool seek_data = (whence == SEEK_DATA);
2595 struct page *page;
2596
2597 if (end <= start)
2598 return -ENXIO;
2599
2600 rcu_read_lock();
2601 while ((page = find_get_entry(&xas, max, XA_PRESENT))) {
2602 loff_t pos = xas.xa_index * PAGE_SIZE;
2603
2604 if (start < pos) {
2605 if (!seek_data)
2606 goto unlock;
2607 start = pos;
2608 }
2609
2610 if (page_seek_match(page, seek_data))
2611 goto unlock;
2612 start = pos + seek_page_size(&xas, page);
2613 if (!xa_is_value(page))
2614 put_page(page);
2615 }
2616 rcu_read_unlock();
2617
2618 if (seek_data)
2619 return -ENXIO;
2620 goto out;
2621
2622unlock:
2623 rcu_read_unlock();
2624 if (!xa_is_value(page))
2625 put_page(page);
2626out:
2627 if (start > end)
2628 return end;
2629 return start;
2630}
2631
2556#ifdef CONFIG_MMU
2557#define MMAP_LOTSAMISS (100)
2558/*
2559 * lock_page_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock
2560 * @vmf - the vm_fault for this fault.
2561 * @page - the page to lock.
2562 * @fpin - the pointer to the file we may pin (or is already pinned).
2563 *

--- 1052 unchanged lines hidden --- 		2632#ifdef CONFIG_MMU
2633#define MMAP_LOTSAMISS (100)
2634/*
2635 * lock_page_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock
2636 * @vmf - the vm_fault for this fault.
2637 * @page - the page to lock.
2638 * @fpin - the pointer to the file we may pin (or is already pinned).
2639 *

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