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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
745 lines
21 KiB
C
745 lines
21 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 <linux/cleancache.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_page().
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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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int i;
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bio_for_each_segment_all(bv, bio, i) {
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struct page *page = bv->bv_page;
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page_endio(page, op_is_write(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(int op, int op_flags, struct bio *bio)
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{
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bio->bi_end_io = mpage_end_io;
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bio_set_op_attrs(bio, op, op_flags);
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guard_bio_eod(op, bio);
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submit_bio(bio);
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return NULL;
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}
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static struct bio *
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mpage_alloc(struct block_device *bdev,
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sector_t first_sector, int nr_vecs,
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gfp_t gfp_flags)
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{
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struct bio *bio;
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/* Restrict the given (page cache) mask for slab allocations */
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gfp_flags &= GFP_KERNEL;
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bio = bio_alloc(gfp_flags, nr_vecs);
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if (bio == NULL && (current->flags & PF_MEMALLOC)) {
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while (!bio && (nr_vecs /= 2))
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bio = bio_alloc(gfp_flags, nr_vecs);
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}
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if (bio) {
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bio_set_dev(bio, bdev);
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bio->bi_iter.bi_sector = first_sector;
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}
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return bio;
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}
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/*
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* support function for mpage_readpages. 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 readpage 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
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map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
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{
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struct inode *inode = page->mapping->host;
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struct buffer_head *page_bh, *head;
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int block = 0;
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if (!page_has_buffers(page)) {
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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 page and the page 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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SetPageUptodate(page);
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return;
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}
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create_empty_buffers(page, i_blocksize(inode), 0);
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}
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head = page_buffers(page);
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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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/*
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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 *
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do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
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sector_t *last_block_in_bio, struct buffer_head *map_bh,
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unsigned long *first_logical_block, get_block_t get_block,
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gfp_t gfp)
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{
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struct inode *inode = page->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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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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unsigned nblocks;
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unsigned relative_block;
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if (page_has_buffers(page))
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goto confused;
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block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
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last_block = block_in_file + 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) && block_in_file > *first_logical_block &&
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block_in_file < (*first_logical_block + nblocks)) {
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unsigned map_offset = block_in_file - *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 page.
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*/
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map_bh->b_page = page;
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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 (get_block(inode, block_in_file, map_bh, 0))
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goto confused;
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*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_page copies the data
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* we just collected from get_block into the page's buffers
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* so readpage 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_page(page, 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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zero_user_segment(page, first_hole << blkbits, PAGE_SIZE);
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if (first_hole == 0) {
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SetPageUptodate(page);
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unlock_page(page);
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goto out;
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}
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} else if (fully_mapped) {
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SetPageMappedToDisk(page);
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}
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if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
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cleancache_get_page(page) == 0) {
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SetPageUptodate(page);
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goto confused;
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}
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/*
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* This page will go to BIO. Do we need to send this BIO off first?
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*/
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if (bio && (*last_block_in_bio != blocks[0] - 1))
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bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
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alloc_new:
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if (bio == NULL) {
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if (first_hole == blocks_per_page) {
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if (!bdev_read_page(bdev, blocks[0] << (blkbits - 9),
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page))
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goto out;
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}
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bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
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min_t(int, nr_pages, BIO_MAX_PAGES), gfp);
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if (bio == NULL)
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goto confused;
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}
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length = first_hole << blkbits;
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if (bio_add_page(bio, page, length, 0) < length) {
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bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
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goto alloc_new;
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}
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relative_block = block_in_file - *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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bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
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else
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*last_block_in_bio = blocks[blocks_per_page - 1];
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out:
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return bio;
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confused:
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if (bio)
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bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
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if (!PageUptodate(page))
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block_read_full_page(page, get_block);
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else
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unlock_page(page);
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goto out;
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}
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/**
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* mpage_readpages - populate an address space with some pages & start reads against them
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* @mapping: the address_space
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* @pages: The address of a list_head which contains the target pages. These
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* pages have their ->index populated and are otherwise uninitialised.
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* The page at @pages->prev has the lowest file offset, and reads should be
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* issued in @pages->prev to @pages->next order.
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* @nr_pages: The number of pages at *@pages
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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
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* the disk mappings may require I/O. Reads of indirect blocks, for example.
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*
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* So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be
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* submitted in the following order:
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*
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* 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16
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*
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* because the indirect block has to be read to get the mappings of blocks
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* 13,14,15,16. Obviously, this impacts performance.
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*
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* So what we do it to allow the filesystem's get_block() function to set
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* BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block
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* after this one will require I/O against a block which is probably close to
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* this one. So you should push what I/O you have currently accumulated.
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*
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* This all causes the disk requests to be issued in the correct order.
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*/
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int
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mpage_readpages(struct address_space *mapping, struct list_head *pages,
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unsigned nr_pages, get_block_t get_block)
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{
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struct bio *bio = NULL;
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unsigned page_idx;
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sector_t last_block_in_bio = 0;
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struct buffer_head map_bh;
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unsigned long first_logical_block = 0;
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gfp_t gfp = readahead_gfp_mask(mapping);
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map_bh.b_state = 0;
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map_bh.b_size = 0;
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for (page_idx = 0; page_idx < nr_pages; page_idx++) {
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struct page *page = lru_to_page(pages);
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prefetchw(&page->flags);
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list_del(&page->lru);
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if (!add_to_page_cache_lru(page, mapping,
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page->index,
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gfp)) {
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bio = do_mpage_readpage(bio, page,
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nr_pages - page_idx,
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&last_block_in_bio, &map_bh,
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&first_logical_block,
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get_block, gfp);
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}
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put_page(page);
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}
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BUG_ON(!list_empty(pages));
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if (bio)
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mpage_bio_submit(REQ_OP_READ, 0, bio);
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return 0;
|
|
}
|
|
EXPORT_SYMBOL(mpage_readpages);
|
|
|
|
/*
|
|
* This isn't called much at all
|
|
*/
|
|
int mpage_readpage(struct page *page, get_block_t get_block)
|
|
{
|
|
struct bio *bio = NULL;
|
|
sector_t last_block_in_bio = 0;
|
|
struct buffer_head map_bh;
|
|
unsigned long first_logical_block = 0;
|
|
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
|
|
|
|
map_bh.b_state = 0;
|
|
map_bh.b_size = 0;
|
|
bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
|
|
&map_bh, &first_logical_block, get_block, gfp);
|
|
if (bio)
|
|
mpage_bio_submit(REQ_OP_READ, 0, bio);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(mpage_readpage);
|
|
|
|
/*
|
|
* 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;
|
|
unsigned use_writepage;
|
|
};
|
|
|
|
/*
|
|
* 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
|
|
* readpage 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);
|
|
}
|
|
|
|
/*
|
|
* 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 page *page, struct writeback_control *wbc,
|
|
void *data)
|
|
{
|
|
struct mpage_data *mpd = data;
|
|
struct bio *bio = mpd->bio;
|
|
struct address_space *mapping = page->mapping;
|
|
struct inode *inode = page->mapping->host;
|
|
const unsigned blkbits = inode->i_blkbits;
|
|
unsigned long end_index;
|
|
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;
|
|
int length;
|
|
struct buffer_head map_bh;
|
|
loff_t i_size = i_size_read(inode);
|
|
int ret = 0;
|
|
int op_flags = wbc_to_write_flags(wbc);
|
|
|
|
if (page_has_buffers(page)) {
|
|
struct buffer_head *head = page_buffers(page);
|
|
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
|
|
* __set_page_dirty_buffers -> 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_page(). If this address_space is also
|
|
* using mpage_readpages then this can rarely happen.
|
|
*/
|
|
goto confused;
|
|
}
|
|
|
|
/*
|
|
* The page has no buffers: map it to disk
|
|
*/
|
|
BUG_ON(!PageUptodate(page));
|
|
block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
|
|
last_block = (i_size - 1) >> blkbits;
|
|
map_bh.b_page = page;
|
|
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_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:
|
|
end_index = i_size >> PAGE_SHIFT;
|
|
if (page->index >= end_index) {
|
|
/*
|
|
* 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."
|
|
*/
|
|
unsigned offset = i_size & (PAGE_SIZE - 1);
|
|
|
|
if (page->index > end_index || !offset)
|
|
goto confused;
|
|
zero_user_segment(page, offset, PAGE_SIZE);
|
|
}
|
|
|
|
/*
|
|
* 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(REQ_OP_WRITE, op_flags, bio);
|
|
|
|
alloc_new:
|
|
if (bio == NULL) {
|
|
if (first_unmapped == blocks_per_page) {
|
|
if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9),
|
|
page, wbc))
|
|
goto out;
|
|
}
|
|
bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
|
|
BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH);
|
|
if (bio == NULL)
|
|
goto confused;
|
|
|
|
wbc_init_bio(wbc, bio);
|
|
bio->bi_write_hint = inode->i_write_hint;
|
|
}
|
|
|
|
/*
|
|
* 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_io(wbc, page, PAGE_SIZE);
|
|
length = first_unmapped << blkbits;
|
|
if (bio_add_page(bio, page, length, 0) < length) {
|
|
bio = mpage_bio_submit(REQ_OP_WRITE, op_flags, bio);
|
|
goto alloc_new;
|
|
}
|
|
|
|
clean_buffers(page, first_unmapped);
|
|
|
|
BUG_ON(PageWriteback(page));
|
|
set_page_writeback(page);
|
|
unlock_page(page);
|
|
if (boundary || (first_unmapped != blocks_per_page)) {
|
|
bio = mpage_bio_submit(REQ_OP_WRITE, op_flags, 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(REQ_OP_WRITE, op_flags, bio);
|
|
|
|
if (mpd->use_writepage) {
|
|
ret = mapping->a_ops->writepage(page, wbc);
|
|
} else {
|
|
ret = -EAGAIN;
|
|
goto out;
|
|
}
|
|
/*
|
|
* The caller has a ref on the inode, so *mapping is stable
|
|
*/
|
|
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.
|
|
* If this is NULL then use a_ops->writepage. Otherwise, go
|
|
* direct-to-BIO.
|
|
*
|
|
* This is a library function, which implements the writepages()
|
|
* address_space_operation.
|
|
*
|
|
* If a page is already under I/O, generic_writepages() skips it, even
|
|
* if it's dirty. This is desirable behaviour for memory-cleaning writeback,
|
|
* but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
|
|
* and msync() need to guarantee that all the data which was dirty at the time
|
|
* the call was made get new I/O started against them. If wbc->sync_mode is
|
|
* WB_SYNC_ALL then we were called for data integrity and we must wait for
|
|
* existing IO to complete.
|
|
*/
|
|
int
|
|
mpage_writepages(struct address_space *mapping,
|
|
struct writeback_control *wbc, get_block_t get_block)
|
|
{
|
|
struct blk_plug plug;
|
|
int ret;
|
|
|
|
blk_start_plug(&plug);
|
|
|
|
if (!get_block)
|
|
ret = generic_writepages(mapping, wbc);
|
|
else {
|
|
struct mpage_data mpd = {
|
|
.bio = NULL,
|
|
.last_block_in_bio = 0,
|
|
.get_block = get_block,
|
|
.use_writepage = 1,
|
|
};
|
|
|
|
ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
|
|
if (mpd.bio) {
|
|
int op_flags = (wbc->sync_mode == WB_SYNC_ALL ?
|
|
REQ_SYNC : 0);
|
|
mpage_bio_submit(REQ_OP_WRITE, op_flags, mpd.bio);
|
|
}
|
|
}
|
|
blk_finish_plug(&plug);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(mpage_writepages);
|
|
|
|
int mpage_writepage(struct page *page, get_block_t get_block,
|
|
struct writeback_control *wbc)
|
|
{
|
|
struct mpage_data mpd = {
|
|
.bio = NULL,
|
|
.last_block_in_bio = 0,
|
|
.get_block = get_block,
|
|
.use_writepage = 0,
|
|
};
|
|
int ret = __mpage_writepage(page, wbc, &mpd);
|
|
if (mpd.bio) {
|
|
int op_flags = (wbc->sync_mode == WB_SYNC_ALL ?
|
|
REQ_SYNC : 0);
|
|
mpage_bio_submit(REQ_OP_WRITE, op_flags, mpd.bio);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(mpage_writepage);
|