From 22098763a10d9c1340827fcf6edab66f153b27f0 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 13 Sep 2026 12:27:00 -0700 Subject: Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Don't destroy user event fields when removal fails User event fields are destroyed before the event is removed from visibility. But that can fail leaving the still visible event with no fields. Move the destroying of the fields to after the event is successfully removed from visibility. - Initialize function graph state is fork before calling copy_exec_state() For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state. If that allocation fails, ftrace_graph_exit_task() will free the tasks ret_stack pointer. Since that pointer is still using the parent's ret_stack, it mistakenly frees the parent's pointer too. Call ftrace_graph_init() on the task first which will NULL out the new tasks's ret_stack and if the copy fails, it will not free anything. - Remove FGRAPH_MAX_INDEX The macro FGRAPH_MAX_INDEX was added but never used. Remove it. - Save ent_size in function graph printing of nested functions The function graph tracer needs to look at the next event to see if the next event is the return of the current function entry. If it is, it prints a single line: ktime_get(); Otherwise it prints it like a nested function: tick_nohz_irq_exit() { ktime_get(); kcpustat_irq_exit(); } In order to look at the next event, it must save the current event so that it has the information to print from it. It saves the event in the iterator descriptor called "ent". What it doesn't save is the ent_size of the event which is now used to know if the function graph arguments are to be printed. The peek doesn't save the size so the size used happens to be that of the size of the last event that was seen. Save the entry event size in the iterator descriptor so that the correct size is used. - Fix several errors with freeing data in the histogram code The histogram code had a lot of leaked or or incorrect accounting when failures happen. Correct them. - Fix histogram regression of .percent and .graph modifiers Up until 6.3 histogram values could have "percent" or "graph" modifiers that changed how they were printed. But a change that added restricting histograms values from being strings, stack traces and other modifiers inadvertently prevented them from using the percent and graph modifiers, which were legal use cases for values. Put back the percent and graph modifiers. - Fix various typos in the comments - Set the trace_clock before initializing a histogram with clock argument The histogram API allows the user to specific which trace clock to use via a "clock=" string. The histogram is set up first before the clock is checked. If the passed in clock is not valid, it exits without fully fixing up the histogram leaving it on the list and a use-after-free can trigger. Update the clock argument first and if it fails then exit gracefully before the histogram trigger is placed on any lists. - Restore :mod: trailer after parsing in ftrace_set_clr_event The function ftrace_set_clr_event() modifies the parse string and needs to put it back to what was passed in. It searches for ":mod:" via a strsep() but fails to put back the first ':' in the string. Add back the ':' in the passed in string. - Take trace_array reference when opening a tracer options file The options files are dynamically created and some tracers add their own options. When a tracer adds their own list of options, the trace_array holding them has an array to hold the list of options for each tracer. This array increases in size via a krealloc(), and the new entry gets a newly allocated array to hold the options of the new tracer being added. The element in each entry of the tracer's option array holds a pointer back to the trace_array, a pointer to the tracer it is associated to, a pointer to the flags of the option. The issue is that these arrays are freed when the trace_array is freed when its instance it represents is removed from the instances directory. There's a race that an open of one of these options files can happen when the instance is being removed. Add a new helper function to be called by the open function of the options file to iterate all existing trace_arrays under a lock and find the one that has the given option element in one of it's tracer arrays. If found, then update the associated trace_array's reference counter to keep it from being freed. If not found, have the open call return -ENODEV. - Disable interrupts when acquiring the lock in rb_wake_up_waiters() The function rb_wake_up_waiters() assumes it will be called in interrupt context and does not disable irqs when taking cpu_buffer->reader_lock, which can be called in hard interrupt context. The issue is in PREEMPT_RT, this function is called in thread context leaving this lock open to a deadlock. Take the lock with interrupts disabled. - Use rcu_assign_pointer() for tmp_ops filter hash The tmp_ops used in update_ftrace_direct_mod() assigns its filter_hash field directly, but that field is annotated as __rcu and sparse complains. Assign it with rcu_assign_pointer() - Fix use-after-free in enable_trigger_private_data_free() The trace_event_call is accessed through the event_trigger_data's trace_event_file pointer to put the trace_event_call on freeing. The issue is that the trace_event_file data may have been freed already causing a use-after-free. Add a field to the event_trigger_data that points directly to the trace_event_call so that it can decrement its reference directly without needing to go through the trace_event_file. - Fix accounting of buffer data remote headers trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount the number of pages is needed for the asked for size as it doesn't take into account the meta data on each page. Add a helper function to do the calculation properly and use that in these functions. - Catch nr_page_va overflow in ring_buffer_desc sizing The number of pages per remote ring buffer is capped by ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to overflow that field would silently allocate a descriptor smaller than what was asked for. - Do not resize the subbuf order if any per_cpu buffer is disabled The mmapping of ring buffers disables resizing the subbuffers, but it is done per-cpu whereas the subbuf size change is done for all the per_cpu buffers under the buffer->mutex. It could change the size of some while the mapping is happening on others. Have the resize of the subbuf order check all the per_cpu buffers under the lock to see if any of them is disabled before starting and causing an inconsistency between buffers that are being mapped. * tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits) ring-buffer: Check resize_disabled before publishing the new subbuf order tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing tracing/remotes: Account for ring buffer page header in size calculation tracing: Don't dereference trace_event_file in deferred trigger free ftrace: Use rcu_assign_pointer() for tmp_ops filter hash ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters() tracing: Take trace_array reference when opening a tracer options file tracing: Fix ring_buffer_read_page_size() kernel-doc tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event() tracing: Fix memory corruption from a "STACKTRACE" histogram key tracing: Fix memory corruption from the histogram stacktrace modifier tracing: Undo the registration when enabling the histogram trigger fails tracing: Take the reference before publishing the named histogram trigger tracing: Set the trace clock before registering the histogram trigger tracing: Fix typo "preceeded" in comment tracing: Fix typo "availabe" in comment tracing: Let histogram values keep the percent and graph modifiers tracing: Keep the entry count when the histogram stats allocation fails tracing: Free histogram the field rejected for a bad modifier tracing: Free histogram the var ref when its initialization fails ... --- fs/mpage.c | 693 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 693 insertions(+) create mode 100644 fs/mpage.c (limited to 'fs/mpage.c') diff --git a/fs/mpage.c b/fs/mpage.c new file mode 100644 index 000000000..f02d8ebd7 --- /dev/null +++ b/fs/mpage.c @@ -0,0 +1,693 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/mpage.c + * + * Copyright (C) 2002, Linus Torvalds. + * + * Contains functions related to preparing and submitting BIOs which contain + * multiple pagecache pages. + * + * 15May2002 Andrew Morton + * Initial version + * 27Jun2002 axboe@suse.de + * use bio_add_page() to build bio's just the right size + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +/* + * I/O completion handler for multipage BIOs. + * + * The mpage code never puts partial pages into a BIO (except for end-of-file). + * If a page does not map to a contiguous run of blocks then it simply falls + * back to block_read_full_folio(). + * + * Why is this? If a page's completion depends on a number of different BIOs + * which can complete in any order (or at the same time) then determining the + * status of that page is hard. See end_buffer_async_read() for the details. + * There is no point in duplicating all that complexity. + */ +static void mpage_read_end_io(struct bio *bio) +{ + struct folio_iter fi; + int err = blk_status_to_errno(bio->bi_status); + + bio_for_each_folio_all(fi, bio) + folio_end_read(fi.folio, err == 0); + + bio_put(bio); +} + +static void mpage_write_end_io(struct bio *bio) +{ + struct folio_iter fi; + int err = blk_status_to_errno(bio->bi_status); + + bio_for_each_folio_all(fi, bio) { + if (err) + mapping_set_error(fi.folio->mapping, err); + folio_end_writeback(fi.folio); + } + + bio_put(bio); +} + +static struct bio *mpage_bio_submit_read(struct bio *bio) +{ + bio->bi_end_io = mpage_read_end_io; + guard_bio_eod(bio); + submit_bio(bio); + return NULL; +} + +static struct bio *mpage_bio_submit_write(struct bio *bio) +{ + bio->bi_end_io = mpage_write_end_io; + guard_bio_eod(bio); + submit_bio(bio); + return NULL; +} + +/* + * support function for mpage_readahead. The fs supplied get_block might + * return an up to date buffer. This is used to map that buffer into + * the page, which allows read_folio to avoid triggering a duplicate call + * to get_block. + * + * The idea is to avoid adding buffers to pages that don't already have + * them. So when the buffer is up to date and the page size == block size, + * this marks the page up to date instead of adding new buffers. + */ +static void map_buffer_to_folio(struct folio *folio, struct buffer_head *bh, + int page_block) +{ + struct inode *inode = folio->mapping->host; + struct buffer_head *page_bh, *head; + int block = 0; + + head = folio_buffers(folio); + if (!head) { + /* + * don't make any buffers if there is only one buffer on + * the folio and the folio just needs to be set up to date + */ + if (inode->i_blkbits == folio_shift(folio) && + buffer_uptodate(bh)) { + folio_mark_uptodate(folio); + return; + } + head = create_empty_buffers(folio, i_blocksize(inode), 0); + } + + page_bh = head; + do { + if (block == page_block) { + page_bh->b_state = bh->b_state; + page_bh->b_bdev = bh->b_bdev; + page_bh->b_blocknr = bh->b_blocknr; + break; + } + page_bh = page_bh->b_this_page; + block++; + } while (page_bh != head); +} + +struct mpage_readpage_args { + struct bio *bio; + struct folio *folio; + unsigned int nr_pages; + bool is_readahead; + sector_t last_block_in_bio; + struct buffer_head map_bh; + unsigned long first_logical_block; + get_block_t *get_block; +}; + +/* + * This is the worker routine which does all the work of mapping the disk + * blocks and constructs largest possible bios, submits them for IO if the + * blocks are not contiguous on the disk. + * + * We pass a buffer_head back and forth and use its buffer_mapped() flag to + * represent the validity of its disk mapping and to decide when to do the next + * get_block() call. + */ +static void do_mpage_readpage(struct mpage_readpage_args *args) +{ + struct folio *folio = args->folio; + struct inode *inode = folio->mapping->host; + const unsigned blkbits = inode->i_blkbits; + const unsigned blocks_per_folio = folio_size(folio) >> blkbits; + const unsigned blocksize = 1 << blkbits; + struct buffer_head *map_bh = &args->map_bh; + sector_t block_in_file; + sector_t last_block; + sector_t last_block_in_file; + sector_t first_block; + unsigned page_block; + unsigned first_hole = blocks_per_folio; + struct block_device *bdev = NULL; + int length; + int fully_mapped = 1; + blk_opf_t opf = REQ_OP_READ; + unsigned nblocks; + unsigned relative_block; + gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL); + + if (args->is_readahead) { + opf |= REQ_RAHEAD; + gfp |= __GFP_NORETRY | __GFP_NOWARN; + } + + if (folio_buffers(folio)) + goto confused; + + block_in_file = folio_pos(folio) >> blkbits; + last_block = block_in_file + ((args->nr_pages * PAGE_SIZE) >> blkbits); + last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits; + if (last_block > last_block_in_file) + last_block = last_block_in_file; + page_block = 0; + + /* + * Map blocks using the result from the previous get_blocks call first. + */ + nblocks = map_bh->b_size >> blkbits; + if (buffer_mapped(map_bh) && + block_in_file > args->first_logical_block && + block_in_file < (args->first_logical_block + nblocks)) { + unsigned map_offset = block_in_file - args->first_logical_block; + unsigned last = nblocks - map_offset; + + first_block = map_bh->b_blocknr + map_offset; + for (relative_block = 0; ; relative_block++) { + if (relative_block == last) { + clear_buffer_mapped(map_bh); + break; + } + if (page_block == blocks_per_folio) + break; + page_block++; + block_in_file++; + } + bdev = map_bh->b_bdev; + } + + /* + * Then do more get_blocks calls until we are done with this folio. + */ + map_bh->b_folio = folio; + while (page_block < blocks_per_folio) { + map_bh->b_state = 0; + map_bh->b_size = 0; + + if (block_in_file < last_block) { + map_bh->b_size = (last_block-block_in_file) << blkbits; + if (args->get_block(inode, block_in_file, map_bh, 0)) + goto confused; + args->first_logical_block = block_in_file; + } + + if (!buffer_mapped(map_bh)) { + fully_mapped = 0; + if (first_hole == blocks_per_folio) + first_hole = page_block; + page_block++; + block_in_file++; + continue; + } + + /* some filesystems will copy data into the page during + * the get_block call, in which case we don't want to + * read it again. map_buffer_to_folio copies the data + * we just collected from get_block into the folio's buffers + * so read_folio doesn't have to repeat the get_block call + */ + if (buffer_uptodate(map_bh)) { + map_buffer_to_folio(folio, map_bh, page_block); + goto confused; + } + + if (first_hole != blocks_per_folio) + goto confused; /* hole -> non-hole */ + + /* Contiguous blocks? */ + if (!page_block) + first_block = map_bh->b_blocknr; + else if (first_block + page_block != map_bh->b_blocknr) + goto confused; + nblocks = map_bh->b_size >> blkbits; + for (relative_block = 0; ; relative_block++) { + if (relative_block == nblocks) { + clear_buffer_mapped(map_bh); + break; + } else if (page_block == blocks_per_folio) + break; + page_block++; + block_in_file++; + } + bdev = map_bh->b_bdev; + } + + if (first_hole != blocks_per_folio) { + folio_zero_segment(folio, first_hole << blkbits, folio_size(folio)); + if (first_hole == 0) { + folio_mark_uptodate(folio); + folio_unlock(folio); + goto out; + } + } else if (fully_mapped) { + folio_set_mappedtodisk(folio); + } + + /* + * This folio will go to BIO. Do we need to send this BIO off first? + */ + if (args->bio && (args->last_block_in_bio != first_block - 1)) + args->bio = mpage_bio_submit_read(args->bio); + +alloc_new: + if (args->bio == NULL) { + args->bio = bio_alloc(bdev, bio_max_segs(args->nr_pages), opf, + gfp); + if (args->bio == NULL) + goto confused; + args->bio->bi_iter.bi_sector = first_block << (blkbits - 9); + } + + length = first_hole << blkbits; + if (!bio_add_folio(args->bio, folio, length, 0)) { + args->bio = mpage_bio_submit_read(args->bio); + goto alloc_new; + } + + relative_block = block_in_file - args->first_logical_block; + nblocks = map_bh->b_size >> blkbits; + if ((buffer_boundary(map_bh) && relative_block == nblocks) || + (first_hole != blocks_per_folio)) + args->bio = mpage_bio_submit_read(args->bio); + else + args->last_block_in_bio = first_block + blocks_per_folio - 1; +out: + return; + +confused: + if (args->bio) + args->bio = mpage_bio_submit_read(args->bio); + if (!folio_test_uptodate(folio)) + block_read_full_folio(folio, args->get_block); + else + folio_unlock(folio); + goto out; +} + +/** + * mpage_readahead - start reads against pages + * @rac: Describes which pages to read. + * @get_block: The filesystem's block mapper function. + * + * This function walks the pages and the blocks within each page, building and + * emitting large BIOs. + * + * If anything unusual happens, such as: + * + * - encountering a page which has buffers + * - encountering a page which has a non-hole after a hole + * - encountering a page with non-contiguous blocks + * + * then this code just gives up and calls the buffer_head-based read function. + * It does handle a page which has holes at the end - that is a common case: + * the end-of-file on blocksize < PAGE_SIZE setups. + * + * BH_Boundary explanation: + * + * There is a problem. The mpage read code assembles several pages, gets all + * 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); + do_mpage_readpage(&args); + /* + * If read ahead failed synchronously, it may cause by removed + * device, or some filesystem metadata error. + */ + if (!folio_test_locked(folio) && !folio_test_uptodate(folio)) + break; + } + if (args.bio) + mpage_bio_submit_read(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 = folio_nr_pages(folio), + .get_block = get_block, + }; + + do_mpage_readpage(&args); + if (args.bio) + mpage_bio_submit_read(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 folio *folio, unsigned first_unmapped) +{ + unsigned buffer_counter = 0; + struct buffer_head *bh, *head = folio_buffers(folio); + + if (!head) + return; + 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 && folio_test_uptodate(folio)) + try_to_free_buffers(folio); +} + +static int mpage_write_folio(struct writeback_control *wbc, struct folio *folio, + struct mpage_data *mpd) +{ + 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_folio = folio_size(folio) >> blkbits; + sector_t last_block; + sector_t block_in_file; + sector_t first_block; + unsigned page_block; + unsigned first_unmapped = blocks_per_folio; + 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_folio) + first_unmapped = page_block; + continue; + } + + if (first_unmapped != blocks_per_folio) + goto confused; /* hole -> non-hole */ + + if (!buffer_dirty(bh) || !buffer_uptodate(bh)) + goto confused; + if (page_block) { + if (bh->b_blocknr != first_block + page_block) + goto confused; + } else { + first_block = bh->b_blocknr; + } + page_block++; + 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 = folio_pos(folio) >> 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_folio; ) { + + 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 != first_block + page_block) + goto confused; + } else { + first_block = map_bh.b_blocknr; + } + page_block++; + 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 != first_block - 1) + bio = mpage_bio_submit_write(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 = first_block << (blkbits - 9); + 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_cgroup_owner(wbc, folio, folio_size(folio)); + length = first_unmapped << blkbits; + if (!bio_add_folio(bio, folio, length, 0)) { + bio = mpage_bio_submit_write(bio); + goto alloc_new; + } + + clean_buffers(folio, first_unmapped); + + BUG_ON(folio_test_writeback(folio)); + folio_start_writeback(folio); + folio_unlock(folio); + if (boundary || (first_unmapped != blocks_per_folio)) { + bio = mpage_bio_submit_write(bio); + if (boundary_block) { + write_boundary_block(boundary_bdev, + boundary_block, 1 << blkbits); + } + } else { + mpd->last_block_in_bio = first_block + blocks_per_folio - 1; + } + goto out; + +confused: + if (bio) + bio = mpage_bio_submit_write(bio); + + /* + * The caller has a ref on the inode, so *mapping is stable + */ + ret = block_write_full_folio(folio, wbc, mpd->get_block); + 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. + * @write_folio: handler to call for each folio before calling + * mpage_write_folio() + * + * This is a library function, which implements the writepages() + * address_space_operation. It calls @write_folio handler for each folio. If + * the handler returns value > 0, it calls mpage_write_folio() to do the + * folio writeback. + */ +int +__mpage_writepages(struct address_space *mapping, + struct writeback_control *wbc, get_block_t get_block, + int (*write_folio)(struct folio *folio, + struct writeback_control *wbc)) +{ + struct mpage_data mpd = { + .get_block = get_block, + }; + struct folio *folio = NULL; + struct blk_plug plug; + int error; + + blk_start_plug(&plug); + while ((folio = writeback_iter(mapping, wbc, folio, &error))) { + if (write_folio) { + error = write_folio(folio, wbc); + /* + * == 0 means folio is handled, < 0 means error. In + * both cases hand back control to writeback_iter() + */ + if (error <= 0) + continue; + /* Let mpage_write_folio() handle the folio. */ + } + error = mpage_write_folio(wbc, folio, &mpd); + } + if (mpd.bio) + mpage_bio_submit_write(mpd.bio); + blk_finish_plug(&plug); + return error; +} +EXPORT_SYMBOL(__mpage_writepages); -- cgit v1.3.1