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![Linus Torvalds](/assets/img/avatar_default.png)
F_SEAL_EXEC") which permits the setting of the memfd execute bit at memfd creation time, with the option of sealing the state of the X bit. - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare") which addresses a rare race condition related to PMD unsharing. - Several folioification patch serieses from Matthew Wilcox, Vishal Moola, Sidhartha Kumar and Lorenzo Stoakes - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which does perform some memcg maintenance and cleanup work. - SeongJae Park has added DAMOS filtering to DAMON, with the series "mm/damon/core: implement damos filter". These filters provide users with finer-grained control over DAMOS's actions. SeongJae has also done some DAMON cleanup work. - Kairui Song adds a series ("Clean up and fixes for swap"). - Vernon Yang contributed the series "Clean up and refinement for maple tree". - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It adds to MGLRU an LRU of memcgs, to improve the scalability of global reclaim. - David Hildenbrand has added some userfaultfd cleanup work in the series "mm: uffd-wp + change_protection() cleanups". - Christoph Hellwig has removed the generic_writepages() library function in the series "remove generic_writepages". - Baolin Wang has performed some maintenance on the compaction code in his series "Some small improvements for compaction". - Sidhartha Kumar is doing some maintenance work on struct page in his series "Get rid of tail page fields". - David Hildenbrand contributed some cleanup, bugfixing and generalization of pte management and of pte debugging in his series "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs". - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation flag in the series "Discard __GFP_ATOMIC". - Sergey Senozhatsky has improved zsmalloc's memory utilization with his series "zsmalloc: make zspage chain size configurable". - Joey Gouly has added prctl() support for prohibiting the creation of writeable+executable mappings. The previous BPF-based approach had shortcomings. See "mm: In-kernel support for memory-deny-write-execute (MDWE)". - Waiman Long did some kmemleak cleanup and bugfixing in the series "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF". - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series "mm: multi-gen LRU: improve". - Jiaqi Yan has provided some enhancements to our memory error statistics reporting, mainly by presenting the statistics on a per-node basis. See the series "Introduce per NUMA node memory error statistics". - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog regression in compaction via his series "Fix excessive CPU usage during compaction". - Christoph Hellwig does some vmalloc maintenance work in the series "cleanup vfree and vunmap". - Christoph Hellwig has removed block_device_operations.rw_page() in ths series "remove ->rw_page". - We get some maple_tree improvements and cleanups in Liam Howlett's series "VMA tree type safety and remove __vma_adjust()". - Suren Baghdasaryan has done some work on the maintainability of our vm_flags handling in the series "introduce vm_flags modifier functions". - Some pagemap cleanup and generalization work in Mike Rapoport's series "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and "fixups for generic implementation of pfn_valid()" - Baoquan He has done some work to make /proc/vmallocinfo and /proc/kcore better represent the real state of things in his series "mm/vmalloc.c: allow vread() to read out vm_map_ram areas". - Jason Gunthorpe rationalized the GUP system's interface to the rest of the kernel in the series "Simplify the external interface for GUP". - SeongJae Park wishes to migrate people from DAMON's debugfs interface over to its sysfs interface. To support this, we'll temporarily be printing warnings when people use the debugfs interface. See the series "mm/damon: deprecate DAMON debugfs interface". - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes and clean-ups" series. - Huang Ying has provided a dramatic reduction in migration's TLB flush IPI rates with the series "migrate_pages(): batch TLB flushing". - Arnd Bergmann has some objtool fixups in "objtool warning fixes". -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCY/PoPQAKCRDdBJ7gKXxA jlvpAPsFECUBBl20qSue2zCYWnHC7Yk4q9ytTkPB/MMDrFEN9wD/SNKEm2UoK6/K DmxHkn0LAitGgJRS/W9w81yrgig9tAQ= =MlGs -----END PGP SIGNATURE----- Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Daniel Verkamp has contributed a memfd series ("mm/memfd: add F_SEAL_EXEC") which permits the setting of the memfd execute bit at memfd creation time, with the option of sealing the state of the X bit. - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare") which addresses a rare race condition related to PMD unsharing. - Several folioification patch serieses from Matthew Wilcox, Vishal Moola, Sidhartha Kumar and Lorenzo Stoakes - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which does perform some memcg maintenance and cleanup work. - SeongJae Park has added DAMOS filtering to DAMON, with the series "mm/damon/core: implement damos filter". These filters provide users with finer-grained control over DAMOS's actions. SeongJae has also done some DAMON cleanup work. - Kairui Song adds a series ("Clean up and fixes for swap"). - Vernon Yang contributed the series "Clean up and refinement for maple tree". - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It adds to MGLRU an LRU of memcgs, to improve the scalability of global reclaim. - David Hildenbrand has added some userfaultfd cleanup work in the series "mm: uffd-wp + change_protection() cleanups". - Christoph Hellwig has removed the generic_writepages() library function in the series "remove generic_writepages". - Baolin Wang has performed some maintenance on the compaction code in his series "Some small improvements for compaction". - Sidhartha Kumar is doing some maintenance work on struct page in his series "Get rid of tail page fields". - David Hildenbrand contributed some cleanup, bugfixing and generalization of pte management and of pte debugging in his series "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs". - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation flag in the series "Discard __GFP_ATOMIC". - Sergey Senozhatsky has improved zsmalloc's memory utilization with his series "zsmalloc: make zspage chain size configurable". - Joey Gouly has added prctl() support for prohibiting the creation of writeable+executable mappings. The previous BPF-based approach had shortcomings. See "mm: In-kernel support for memory-deny-write-execute (MDWE)". - Waiman Long did some kmemleak cleanup and bugfixing in the series "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF". - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series "mm: multi-gen LRU: improve". - Jiaqi Yan has provided some enhancements to our memory error statistics reporting, mainly by presenting the statistics on a per-node basis. See the series "Introduce per NUMA node memory error statistics". - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog regression in compaction via his series "Fix excessive CPU usage during compaction". - Christoph Hellwig does some vmalloc maintenance work in the series "cleanup vfree and vunmap". - Christoph Hellwig has removed block_device_operations.rw_page() in ths series "remove ->rw_page". - We get some maple_tree improvements and cleanups in Liam Howlett's series "VMA tree type safety and remove __vma_adjust()". - Suren Baghdasaryan has done some work on the maintainability of our vm_flags handling in the series "introduce vm_flags modifier functions". - Some pagemap cleanup and generalization work in Mike Rapoport's series "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and "fixups for generic implementation of pfn_valid()" - Baoquan He has done some work to make /proc/vmallocinfo and /proc/kcore better represent the real state of things in his series "mm/vmalloc.c: allow vread() to read out vm_map_ram areas". - Jason Gunthorpe rationalized the GUP system's interface to the rest of the kernel in the series "Simplify the external interface for GUP". - SeongJae Park wishes to migrate people from DAMON's debugfs interface over to its sysfs interface. To support this, we'll temporarily be printing warnings when people use the debugfs interface. See the series "mm/damon: deprecate DAMON debugfs interface". - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes and clean-ups" series. - Huang Ying has provided a dramatic reduction in migration's TLB flush IPI rates with the series "migrate_pages(): batch TLB flushing". - Arnd Bergmann has some objtool fixups in "objtool warning fixes". * tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits) include/linux/migrate.h: remove unneeded externs mm/memory_hotplug: cleanup return value handing in do_migrate_range() mm/uffd: fix comment in handling pte markers mm: change to return bool for isolate_movable_page() mm: hugetlb: change to return bool for isolate_hugetlb() mm: change to return bool for isolate_lru_page() mm: change to return bool for folio_isolate_lru() objtool: add UACCESS exceptions for __tsan_volatile_read/write kmsan: disable ftrace in kmsan core code kasan: mark addr_has_metadata __always_inline mm: memcontrol: rename memcg_kmem_enabled() sh: initialize max_mapnr m68k/nommu: add missing definition of ARCH_PFN_OFFSET mm: percpu: fix incorrect size in pcpu_obj_full_size() maple_tree: reduce stack usage with gcc-9 and earlier mm: page_alloc: call panic() when memoryless node allocation fails mm: multi-gen LRU: avoid futile retries migrate_pages: move THP/hugetlb migration support check to simplify code migrate_pages: batch flushing TLB migrate_pages: share more code between _unmap and _move ...
659 lines
18 KiB
C
659 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/mpage.c
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*
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* Copyright (C) 2002, Linus Torvalds.
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*
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* Contains functions related to preparing and submitting BIOs which contain
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* multiple pagecache pages.
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*
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* 15May2002 Andrew Morton
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* Initial version
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* 27Jun2002 axboe@suse.de
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* use bio_add_page() to build bio's just the right size
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*/
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/mm.h>
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#include <linux/kdev_t.h>
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#include <linux/gfp.h>
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#include <linux/bio.h>
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/blkdev.h>
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#include <linux/highmem.h>
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#include <linux/prefetch.h>
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#include <linux/mpage.h>
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#include <linux/mm_inline.h>
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#include <linux/writeback.h>
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#include <linux/backing-dev.h>
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#include <linux/pagevec.h>
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#include "internal.h"
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/*
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* I/O completion handler for multipage BIOs.
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*
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* The mpage code never puts partial pages into a BIO (except for end-of-file).
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* If a page does not map to a contiguous run of blocks then it simply falls
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* back to block_read_full_folio().
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*
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* Why is this? If a page's completion depends on a number of different BIOs
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* which can complete in any order (or at the same time) then determining the
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* status of that page is hard. See end_buffer_async_read() for the details.
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* There is no point in duplicating all that complexity.
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*/
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static void mpage_end_io(struct bio *bio)
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{
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struct bio_vec *bv;
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struct bvec_iter_all iter_all;
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bio_for_each_segment_all(bv, bio, iter_all) {
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struct page *page = bv->bv_page;
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page_endio(page, bio_op(bio),
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blk_status_to_errno(bio->bi_status));
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}
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bio_put(bio);
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}
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static struct bio *mpage_bio_submit(struct bio *bio)
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{
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bio->bi_end_io = mpage_end_io;
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guard_bio_eod(bio);
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submit_bio(bio);
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return NULL;
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}
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/*
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* support function for mpage_readahead. The fs supplied get_block might
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* return an up to date buffer. This is used to map that buffer into
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* the page, which allows read_folio to avoid triggering a duplicate call
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* to get_block.
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*
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* The idea is to avoid adding buffers to pages that don't already have
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* them. So when the buffer is up to date and the page size == block size,
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* this marks the page up to date instead of adding new buffers.
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*/
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static void map_buffer_to_folio(struct folio *folio, struct buffer_head *bh,
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int page_block)
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{
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struct inode *inode = folio->mapping->host;
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struct buffer_head *page_bh, *head;
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int block = 0;
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head = folio_buffers(folio);
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if (!head) {
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/*
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* don't make any buffers if there is only one buffer on
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* the folio and the folio just needs to be set up to date
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*/
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if (inode->i_blkbits == PAGE_SHIFT &&
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buffer_uptodate(bh)) {
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folio_mark_uptodate(folio);
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return;
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}
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create_empty_buffers(&folio->page, i_blocksize(inode), 0);
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head = folio_buffers(folio);
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}
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page_bh = head;
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do {
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if (block == page_block) {
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page_bh->b_state = bh->b_state;
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page_bh->b_bdev = bh->b_bdev;
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page_bh->b_blocknr = bh->b_blocknr;
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break;
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}
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page_bh = page_bh->b_this_page;
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block++;
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} while (page_bh != head);
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}
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struct mpage_readpage_args {
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struct bio *bio;
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struct folio *folio;
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unsigned int nr_pages;
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bool is_readahead;
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sector_t last_block_in_bio;
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struct buffer_head map_bh;
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unsigned long first_logical_block;
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get_block_t *get_block;
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};
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/*
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* This is the worker routine which does all the work of mapping the disk
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* blocks and constructs largest possible bios, submits them for IO if the
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* blocks are not contiguous on the disk.
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*
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* We pass a buffer_head back and forth and use its buffer_mapped() flag to
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* represent the validity of its disk mapping and to decide when to do the next
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* get_block() call.
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*/
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static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
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{
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struct folio *folio = args->folio;
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struct inode *inode = folio->mapping->host;
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const unsigned blkbits = inode->i_blkbits;
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const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
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const unsigned blocksize = 1 << blkbits;
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struct buffer_head *map_bh = &args->map_bh;
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sector_t block_in_file;
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sector_t last_block;
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sector_t last_block_in_file;
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sector_t blocks[MAX_BUF_PER_PAGE];
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unsigned page_block;
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unsigned first_hole = blocks_per_page;
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struct block_device *bdev = NULL;
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int length;
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int fully_mapped = 1;
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blk_opf_t opf = REQ_OP_READ;
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unsigned nblocks;
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unsigned relative_block;
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gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
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/* MAX_BUF_PER_PAGE, for example */
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VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
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if (args->is_readahead) {
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opf |= REQ_RAHEAD;
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gfp |= __GFP_NORETRY | __GFP_NOWARN;
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}
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if (folio_buffers(folio))
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goto confused;
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block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits);
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last_block = block_in_file + args->nr_pages * blocks_per_page;
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last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
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if (last_block > last_block_in_file)
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last_block = last_block_in_file;
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page_block = 0;
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/*
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* Map blocks using the result from the previous get_blocks call first.
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*/
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nblocks = map_bh->b_size >> blkbits;
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if (buffer_mapped(map_bh) &&
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block_in_file > args->first_logical_block &&
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block_in_file < (args->first_logical_block + nblocks)) {
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unsigned map_offset = block_in_file - args->first_logical_block;
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unsigned last = nblocks - map_offset;
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for (relative_block = 0; ; relative_block++) {
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if (relative_block == last) {
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clear_buffer_mapped(map_bh);
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break;
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}
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if (page_block == blocks_per_page)
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break;
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blocks[page_block] = map_bh->b_blocknr + map_offset +
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relative_block;
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page_block++;
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block_in_file++;
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}
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bdev = map_bh->b_bdev;
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}
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/*
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* Then do more get_blocks calls until we are done with this folio.
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*/
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map_bh->b_folio = folio;
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while (page_block < blocks_per_page) {
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map_bh->b_state = 0;
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map_bh->b_size = 0;
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if (block_in_file < last_block) {
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map_bh->b_size = (last_block-block_in_file) << blkbits;
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if (args->get_block(inode, block_in_file, map_bh, 0))
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goto confused;
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args->first_logical_block = block_in_file;
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}
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if (!buffer_mapped(map_bh)) {
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fully_mapped = 0;
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if (first_hole == blocks_per_page)
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first_hole = page_block;
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page_block++;
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block_in_file++;
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continue;
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}
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/* some filesystems will copy data into the page during
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* the get_block call, in which case we don't want to
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* read it again. map_buffer_to_folio copies the data
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* we just collected from get_block into the folio's buffers
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* so read_folio doesn't have to repeat the get_block call
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*/
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if (buffer_uptodate(map_bh)) {
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map_buffer_to_folio(folio, map_bh, page_block);
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goto confused;
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}
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if (first_hole != blocks_per_page)
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goto confused; /* hole -> non-hole */
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/* Contiguous blocks? */
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if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
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goto confused;
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nblocks = map_bh->b_size >> blkbits;
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for (relative_block = 0; ; relative_block++) {
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if (relative_block == nblocks) {
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clear_buffer_mapped(map_bh);
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break;
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} else if (page_block == blocks_per_page)
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break;
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blocks[page_block] = map_bh->b_blocknr+relative_block;
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page_block++;
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block_in_file++;
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}
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bdev = map_bh->b_bdev;
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}
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if (first_hole != blocks_per_page) {
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folio_zero_segment(folio, first_hole << blkbits, PAGE_SIZE);
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if (first_hole == 0) {
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folio_mark_uptodate(folio);
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folio_unlock(folio);
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goto out;
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}
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} else if (fully_mapped) {
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folio_set_mappedtodisk(folio);
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}
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/*
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* This folio will go to BIO. Do we need to send this BIO off first?
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*/
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if (args->bio && (args->last_block_in_bio != blocks[0] - 1))
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args->bio = mpage_bio_submit(args->bio);
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alloc_new:
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if (args->bio == NULL) {
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args->bio = bio_alloc(bdev, bio_max_segs(args->nr_pages), opf,
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gfp);
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if (args->bio == NULL)
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goto confused;
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args->bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
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}
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length = first_hole << blkbits;
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if (!bio_add_folio(args->bio, folio, length, 0)) {
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args->bio = mpage_bio_submit(args->bio);
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goto alloc_new;
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}
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relative_block = block_in_file - args->first_logical_block;
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nblocks = map_bh->b_size >> blkbits;
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if ((buffer_boundary(map_bh) && relative_block == nblocks) ||
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(first_hole != blocks_per_page))
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args->bio = mpage_bio_submit(args->bio);
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else
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args->last_block_in_bio = blocks[blocks_per_page - 1];
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out:
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return args->bio;
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confused:
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if (args->bio)
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args->bio = mpage_bio_submit(args->bio);
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if (!folio_test_uptodate(folio))
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block_read_full_folio(folio, args->get_block);
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else
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folio_unlock(folio);
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goto out;
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}
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/**
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* mpage_readahead - start reads against pages
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* @rac: Describes which pages to read.
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* @get_block: The filesystem's block mapper function.
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*
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* This function walks the pages and the blocks within each page, building and
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* emitting large BIOs.
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*
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* If anything unusual happens, such as:
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*
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* - encountering a page which has buffers
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* - encountering a page which has a non-hole after a hole
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* - encountering a page with non-contiguous blocks
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*
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* then this code just gives up and calls the buffer_head-based read function.
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* It does handle a page which has holes at the end - that is a common case:
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* the end-of-file on blocksize < PAGE_SIZE setups.
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*
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* BH_Boundary explanation:
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*
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* There is a problem. The mpage read code assembles several pages, gets all
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|
* their disk mappings, and then submits them all. That's fine, but obtaining
|
|
* the disk mappings may require I/O. Reads of indirect blocks, for example.
|
|
*
|
|
* So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be
|
|
* submitted in the following order:
|
|
*
|
|
* 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16
|
|
*
|
|
* because the indirect block has to be read to get the mappings of blocks
|
|
* 13,14,15,16. Obviously, this impacts performance.
|
|
*
|
|
* So what we do it to allow the filesystem's get_block() function to set
|
|
* BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block
|
|
* after this one will require I/O against a block which is probably close to
|
|
* this one. So you should push what I/O you have currently accumulated.
|
|
*
|
|
* This all causes the disk requests to be issued in the correct order.
|
|
*/
|
|
void mpage_readahead(struct readahead_control *rac, get_block_t get_block)
|
|
{
|
|
struct folio *folio;
|
|
struct mpage_readpage_args args = {
|
|
.get_block = get_block,
|
|
.is_readahead = true,
|
|
};
|
|
|
|
while ((folio = readahead_folio(rac))) {
|
|
prefetchw(&folio->flags);
|
|
args.folio = folio;
|
|
args.nr_pages = readahead_count(rac);
|
|
args.bio = do_mpage_readpage(&args);
|
|
}
|
|
if (args.bio)
|
|
mpage_bio_submit(args.bio);
|
|
}
|
|
EXPORT_SYMBOL(mpage_readahead);
|
|
|
|
/*
|
|
* This isn't called much at all
|
|
*/
|
|
int mpage_read_folio(struct folio *folio, get_block_t get_block)
|
|
{
|
|
struct mpage_readpage_args args = {
|
|
.folio = folio,
|
|
.nr_pages = 1,
|
|
.get_block = get_block,
|
|
};
|
|
|
|
args.bio = do_mpage_readpage(&args);
|
|
if (args.bio)
|
|
mpage_bio_submit(args.bio);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(mpage_read_folio);
|
|
|
|
/*
|
|
* Writing is not so simple.
|
|
*
|
|
* If the page has buffers then they will be used for obtaining the disk
|
|
* mapping. We only support pages which are fully mapped-and-dirty, with a
|
|
* special case for pages which are unmapped at the end: end-of-file.
|
|
*
|
|
* If the page has no buffers (preferred) then the page is mapped here.
|
|
*
|
|
* If all blocks are found to be contiguous then the page can go into the
|
|
* BIO. Otherwise fall back to the mapping's writepage().
|
|
*
|
|
* FIXME: This code wants an estimate of how many pages are still to be
|
|
* written, so it can intelligently allocate a suitably-sized BIO. For now,
|
|
* just allocate full-size (16-page) BIOs.
|
|
*/
|
|
|
|
struct mpage_data {
|
|
struct bio *bio;
|
|
sector_t last_block_in_bio;
|
|
get_block_t *get_block;
|
|
};
|
|
|
|
/*
|
|
* We have our BIO, so we can now mark the buffers clean. Make
|
|
* sure to only clean buffers which we know we'll be writing.
|
|
*/
|
|
static void clean_buffers(struct page *page, unsigned first_unmapped)
|
|
{
|
|
unsigned buffer_counter = 0;
|
|
struct buffer_head *bh, *head;
|
|
if (!page_has_buffers(page))
|
|
return;
|
|
head = page_buffers(page);
|
|
bh = head;
|
|
|
|
do {
|
|
if (buffer_counter++ == first_unmapped)
|
|
break;
|
|
clear_buffer_dirty(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* we cannot drop the bh if the page is not uptodate or a concurrent
|
|
* read_folio would fail to serialize with the bh and it would read from
|
|
* disk before we reach the platter.
|
|
*/
|
|
if (buffer_heads_over_limit && PageUptodate(page))
|
|
try_to_free_buffers(page_folio(page));
|
|
}
|
|
|
|
/*
|
|
* For situations where we want to clean all buffers attached to a page.
|
|
* We don't need to calculate how many buffers are attached to the page,
|
|
* we just need to specify a number larger than the maximum number of buffers.
|
|
*/
|
|
void clean_page_buffers(struct page *page)
|
|
{
|
|
clean_buffers(page, ~0U);
|
|
}
|
|
|
|
static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc,
|
|
void *data)
|
|
{
|
|
struct mpage_data *mpd = data;
|
|
struct bio *bio = mpd->bio;
|
|
struct address_space *mapping = folio->mapping;
|
|
struct inode *inode = mapping->host;
|
|
const unsigned blkbits = inode->i_blkbits;
|
|
const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
|
|
sector_t last_block;
|
|
sector_t block_in_file;
|
|
sector_t blocks[MAX_BUF_PER_PAGE];
|
|
unsigned page_block;
|
|
unsigned first_unmapped = blocks_per_page;
|
|
struct block_device *bdev = NULL;
|
|
int boundary = 0;
|
|
sector_t boundary_block = 0;
|
|
struct block_device *boundary_bdev = NULL;
|
|
size_t length;
|
|
struct buffer_head map_bh;
|
|
loff_t i_size = i_size_read(inode);
|
|
int ret = 0;
|
|
struct buffer_head *head = folio_buffers(folio);
|
|
|
|
if (head) {
|
|
struct buffer_head *bh = head;
|
|
|
|
/* If they're all mapped and dirty, do it */
|
|
page_block = 0;
|
|
do {
|
|
BUG_ON(buffer_locked(bh));
|
|
if (!buffer_mapped(bh)) {
|
|
/*
|
|
* unmapped dirty buffers are created by
|
|
* block_dirty_folio -> mmapped data
|
|
*/
|
|
if (buffer_dirty(bh))
|
|
goto confused;
|
|
if (first_unmapped == blocks_per_page)
|
|
first_unmapped = page_block;
|
|
continue;
|
|
}
|
|
|
|
if (first_unmapped != blocks_per_page)
|
|
goto confused; /* hole -> non-hole */
|
|
|
|
if (!buffer_dirty(bh) || !buffer_uptodate(bh))
|
|
goto confused;
|
|
if (page_block) {
|
|
if (bh->b_blocknr != blocks[page_block-1] + 1)
|
|
goto confused;
|
|
}
|
|
blocks[page_block++] = bh->b_blocknr;
|
|
boundary = buffer_boundary(bh);
|
|
if (boundary) {
|
|
boundary_block = bh->b_blocknr;
|
|
boundary_bdev = bh->b_bdev;
|
|
}
|
|
bdev = bh->b_bdev;
|
|
} while ((bh = bh->b_this_page) != head);
|
|
|
|
if (first_unmapped)
|
|
goto page_is_mapped;
|
|
|
|
/*
|
|
* Page has buffers, but they are all unmapped. The page was
|
|
* created by pagein or read over a hole which was handled by
|
|
* block_read_full_folio(). If this address_space is also
|
|
* using mpage_readahead then this can rarely happen.
|
|
*/
|
|
goto confused;
|
|
}
|
|
|
|
/*
|
|
* The page has no buffers: map it to disk
|
|
*/
|
|
BUG_ON(!folio_test_uptodate(folio));
|
|
block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits);
|
|
/*
|
|
* Whole page beyond EOF? Skip allocating blocks to avoid leaking
|
|
* space.
|
|
*/
|
|
if (block_in_file >= (i_size + (1 << blkbits) - 1) >> blkbits)
|
|
goto page_is_mapped;
|
|
last_block = (i_size - 1) >> blkbits;
|
|
map_bh.b_folio = folio;
|
|
for (page_block = 0; page_block < blocks_per_page; ) {
|
|
|
|
map_bh.b_state = 0;
|
|
map_bh.b_size = 1 << blkbits;
|
|
if (mpd->get_block(inode, block_in_file, &map_bh, 1))
|
|
goto confused;
|
|
if (!buffer_mapped(&map_bh))
|
|
goto confused;
|
|
if (buffer_new(&map_bh))
|
|
clean_bdev_bh_alias(&map_bh);
|
|
if (buffer_boundary(&map_bh)) {
|
|
boundary_block = map_bh.b_blocknr;
|
|
boundary_bdev = map_bh.b_bdev;
|
|
}
|
|
if (page_block) {
|
|
if (map_bh.b_blocknr != blocks[page_block-1] + 1)
|
|
goto confused;
|
|
}
|
|
blocks[page_block++] = map_bh.b_blocknr;
|
|
boundary = buffer_boundary(&map_bh);
|
|
bdev = map_bh.b_bdev;
|
|
if (block_in_file == last_block)
|
|
break;
|
|
block_in_file++;
|
|
}
|
|
BUG_ON(page_block == 0);
|
|
|
|
first_unmapped = page_block;
|
|
|
|
page_is_mapped:
|
|
/* Don't bother writing beyond EOF, truncate will discard the folio */
|
|
if (folio_pos(folio) >= i_size)
|
|
goto confused;
|
|
length = folio_size(folio);
|
|
if (folio_pos(folio) + length > i_size) {
|
|
/*
|
|
* The page straddles i_size. It must be zeroed out on each
|
|
* and every writepage invocation because it may be mmapped.
|
|
* "A file is mapped in multiples of the page size. For a file
|
|
* that is not a multiple of the page size, the remaining memory
|
|
* is zeroed when mapped, and writes to that region are not
|
|
* written out to the file."
|
|
*/
|
|
length = i_size - folio_pos(folio);
|
|
folio_zero_segment(folio, length, folio_size(folio));
|
|
}
|
|
|
|
/*
|
|
* This page will go to BIO. Do we need to send this BIO off first?
|
|
*/
|
|
if (bio && mpd->last_block_in_bio != blocks[0] - 1)
|
|
bio = mpage_bio_submit(bio);
|
|
|
|
alloc_new:
|
|
if (bio == NULL) {
|
|
bio = bio_alloc(bdev, BIO_MAX_VECS,
|
|
REQ_OP_WRITE | wbc_to_write_flags(wbc),
|
|
GFP_NOFS);
|
|
bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
|
|
wbc_init_bio(wbc, bio);
|
|
}
|
|
|
|
/*
|
|
* Must try to add the page before marking the buffer clean or
|
|
* the confused fail path above (OOM) will be very confused when
|
|
* it finds all bh marked clean (i.e. it will not write anything)
|
|
*/
|
|
wbc_account_cgroup_owner(wbc, &folio->page, folio_size(folio));
|
|
length = first_unmapped << blkbits;
|
|
if (!bio_add_folio(bio, folio, length, 0)) {
|
|
bio = mpage_bio_submit(bio);
|
|
goto alloc_new;
|
|
}
|
|
|
|
clean_buffers(&folio->page, first_unmapped);
|
|
|
|
BUG_ON(folio_test_writeback(folio));
|
|
folio_start_writeback(folio);
|
|
folio_unlock(folio);
|
|
if (boundary || (first_unmapped != blocks_per_page)) {
|
|
bio = mpage_bio_submit(bio);
|
|
if (boundary_block) {
|
|
write_boundary_block(boundary_bdev,
|
|
boundary_block, 1 << blkbits);
|
|
}
|
|
} else {
|
|
mpd->last_block_in_bio = blocks[blocks_per_page - 1];
|
|
}
|
|
goto out;
|
|
|
|
confused:
|
|
if (bio)
|
|
bio = mpage_bio_submit(bio);
|
|
|
|
/*
|
|
* The caller has a ref on the inode, so *mapping is stable
|
|
*/
|
|
ret = block_write_full_page(&folio->page, mpd->get_block, wbc);
|
|
mapping_set_error(mapping, ret);
|
|
out:
|
|
mpd->bio = bio;
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* mpage_writepages - walk the list of dirty pages of the given address space & writepage() all of them
|
|
* @mapping: address space structure to write
|
|
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
|
|
* @get_block: the filesystem's block mapper function.
|
|
*
|
|
* This is a library function, which implements the writepages()
|
|
* address_space_operation.
|
|
*/
|
|
int
|
|
mpage_writepages(struct address_space *mapping,
|
|
struct writeback_control *wbc, get_block_t get_block)
|
|
{
|
|
struct mpage_data mpd = {
|
|
.get_block = get_block,
|
|
};
|
|
struct blk_plug plug;
|
|
int ret;
|
|
|
|
blk_start_plug(&plug);
|
|
ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
|
|
if (mpd.bio)
|
|
mpage_bio_submit(mpd.bio);
|
|
blk_finish_plug(&plug);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(mpage_writepages);
|