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authorDarrick J. Wong <darrick.wong@oracle.com>2019-07-15 08:50:59 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-07-17 07:16:00 -0700
commitafc51aaa22f26cb2894083c4f25097e0950f1609 (patch)
tree5cda015482fd64aa7fd4020c004b32ee605cc462 /fs/iomap
parentdb074436f421967f4f30cfbb6fbc2a728f3e62b3 (diff)
iomap: move the buffered IO code into a separate file
Move the buffered IO code into a separate file so that we can group related functions in a single file instead of having a single enormous source file. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/iomap')
-rw-r--r--fs/iomap/Makefile1
-rw-r--r--fs/iomap/buffered-io.c1073
2 files changed, 1074 insertions, 0 deletions
diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
index a67a97758858..19fd672cd486 100644
--- a/fs/iomap/Makefile
+++ b/fs/iomap/Makefile
@@ -6,6 +6,7 @@
obj-$(CONFIG_FS_IOMAP) += iomap.o
iomap-y += \
+ buffered-io.o \
direct-io.o \
fiemap.o \
seek.o
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
new file mode 100644
index 000000000000..da4d958f9dc8
--- /dev/null
+++ b/fs/iomap/buffered-io.c
@@ -0,0 +1,1073 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 Red Hat, Inc.
+ * Copyright (c) 2016-2018 Christoph Hellwig.
+ */
+#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/iomap.h>
+#include <linux/pagemap.h>
+#include <linux/uio.h>
+#include <linux/buffer_head.h>
+#include <linux/dax.h>
+#include <linux/writeback.h>
+#include <linux/swap.h>
+#include <linux/bio.h>
+#include <linux/sched/signal.h>
+#include <linux/migrate.h>
+
+#include "../internal.h"
+
+static struct iomap_page *
+iomap_page_create(struct inode *inode, struct page *page)
+{
+ struct iomap_page *iop = to_iomap_page(page);
+
+ if (iop || i_blocksize(inode) == PAGE_SIZE)
+ return iop;
+
+ iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
+ atomic_set(&iop->read_count, 0);
+ atomic_set(&iop->write_count, 0);
+ bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
+
+ /*
+ * migrate_page_move_mapping() assumes that pages with private data have
+ * their count elevated by 1.
+ */
+ get_page(page);
+ set_page_private(page, (unsigned long)iop);
+ SetPagePrivate(page);
+ return iop;
+}
+
+static void
+iomap_page_release(struct page *page)
+{
+ struct iomap_page *iop = to_iomap_page(page);
+
+ if (!iop)
+ return;
+ WARN_ON_ONCE(atomic_read(&iop->read_count));
+ WARN_ON_ONCE(atomic_read(&iop->write_count));
+ ClearPagePrivate(page);
+ set_page_private(page, 0);
+ put_page(page);
+ kfree(iop);
+}
+
+/*
+ * Calculate the range inside the page that we actually need to read.
+ */
+static void
+iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
+ loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
+{
+ loff_t orig_pos = *pos;
+ loff_t isize = i_size_read(inode);
+ unsigned block_bits = inode->i_blkbits;
+ unsigned block_size = (1 << block_bits);
+ unsigned poff = offset_in_page(*pos);
+ unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
+ unsigned first = poff >> block_bits;
+ unsigned last = (poff + plen - 1) >> block_bits;
+
+ /*
+ * If the block size is smaller than the page size we need to check the
+ * per-block uptodate status and adjust the offset and length if needed
+ * to avoid reading in already uptodate ranges.
+ */
+ if (iop) {
+ unsigned int i;
+
+ /* move forward for each leading block marked uptodate */
+ for (i = first; i <= last; i++) {
+ if (!test_bit(i, iop->uptodate))
+ break;
+ *pos += block_size;
+ poff += block_size;
+ plen -= block_size;
+ first++;
+ }
+
+ /* truncate len if we find any trailing uptodate block(s) */
+ for ( ; i <= last; i++) {
+ if (test_bit(i, iop->uptodate)) {
+ plen -= (last - i + 1) * block_size;
+ last = i - 1;
+ break;
+ }
+ }
+ }
+
+ /*
+ * If the extent spans the block that contains the i_size we need to
+ * handle both halves separately so that we properly zero data in the
+ * page cache for blocks that are entirely outside of i_size.
+ */
+ if (orig_pos <= isize && orig_pos + length > isize) {
+ unsigned end = offset_in_page(isize - 1) >> block_bits;
+
+ if (first <= end && last > end)
+ plen -= (last - end) * block_size;
+ }
+
+ *offp = poff;
+ *lenp = plen;
+}
+
+static void
+iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
+{
+ struct iomap_page *iop = to_iomap_page(page);
+ struct inode *inode = page->mapping->host;
+ unsigned first = off >> inode->i_blkbits;
+ unsigned last = (off + len - 1) >> inode->i_blkbits;
+ unsigned int i;
+ bool uptodate = true;
+
+ if (iop) {
+ for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
+ if (i >= first && i <= last)
+ set_bit(i, iop->uptodate);
+ else if (!test_bit(i, iop->uptodate))
+ uptodate = false;
+ }
+ }
+
+ if (uptodate && !PageError(page))
+ SetPageUptodate(page);
+}
+
+static void
+iomap_read_finish(struct iomap_page *iop, struct page *page)
+{
+ if (!iop || atomic_dec_and_test(&iop->read_count))
+ unlock_page(page);
+}
+
+static void
+iomap_read_page_end_io(struct bio_vec *bvec, int error)
+{
+ struct page *page = bvec->bv_page;
+ struct iomap_page *iop = to_iomap_page(page);
+
+ if (unlikely(error)) {
+ ClearPageUptodate(page);
+ SetPageError(page);
+ } else {
+ iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
+ }
+
+ iomap_read_finish(iop, page);
+}
+
+static void
+iomap_read_end_io(struct bio *bio)
+{
+ int error = blk_status_to_errno(bio->bi_status);
+ struct bio_vec *bvec;
+ struct bvec_iter_all iter_all;
+
+ bio_for_each_segment_all(bvec, bio, iter_all)
+ iomap_read_page_end_io(bvec, error);
+ bio_put(bio);
+}
+
+struct iomap_readpage_ctx {
+ struct page *cur_page;
+ bool cur_page_in_bio;
+ bool is_readahead;
+ struct bio *bio;
+ struct list_head *pages;
+};
+
+static void
+iomap_read_inline_data(struct inode *inode, struct page *page,
+ struct iomap *iomap)
+{
+ size_t size = i_size_read(inode);
+ void *addr;
+
+ if (PageUptodate(page))
+ return;
+
+ BUG_ON(page->index);
+ BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
+
+ addr = kmap_atomic(page);
+ memcpy(addr, iomap->inline_data, size);
+ memset(addr + size, 0, PAGE_SIZE - size);
+ kunmap_atomic(addr);
+ SetPageUptodate(page);
+}
+
+static loff_t
+iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
+ struct iomap *iomap)
+{
+ struct iomap_readpage_ctx *ctx = data;
+ struct page *page = ctx->cur_page;
+ struct iomap_page *iop = iomap_page_create(inode, page);
+ bool same_page = false, is_contig = false;
+ loff_t orig_pos = pos;
+ unsigned poff, plen;
+ sector_t sector;
+
+ if (iomap->type == IOMAP_INLINE) {
+ WARN_ON_ONCE(pos);
+ iomap_read_inline_data(inode, page, iomap);
+ return PAGE_SIZE;
+ }
+
+ /* zero post-eof blocks as the page may be mapped */
+ iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
+ if (plen == 0)
+ goto done;
+
+ if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) {
+ zero_user(page, poff, plen);
+ iomap_set_range_uptodate(page, poff, plen);
+ goto done;
+ }
+
+ ctx->cur_page_in_bio = true;
+
+ /*
+ * Try to merge into a previous segment if we can.
+ */
+ sector = iomap_sector(iomap, pos);
+ if (ctx->bio && bio_end_sector(ctx->bio) == sector)
+ is_contig = true;
+
+ if (is_contig &&
+ __bio_try_merge_page(ctx->bio, page, plen, poff, &same_page)) {
+ if (!same_page && iop)
+ atomic_inc(&iop->read_count);
+ goto done;
+ }
+
+ /*
+ * If we start a new segment we need to increase the read count, and we
+ * need to do so before submitting any previous full bio to make sure
+ * that we don't prematurely unlock the page.
+ */
+ if (iop)
+ atomic_inc(&iop->read_count);
+
+ if (!ctx->bio || !is_contig || bio_full(ctx->bio, plen)) {
+ gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
+ int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+ if (ctx->bio)
+ submit_bio(ctx->bio);
+
+ if (ctx->is_readahead) /* same as readahead_gfp_mask */
+ gfp |= __GFP_NORETRY | __GFP_NOWARN;
+ ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
+ ctx->bio->bi_opf = REQ_OP_READ;
+ if (ctx->is_readahead)
+ ctx->bio->bi_opf |= REQ_RAHEAD;
+ ctx->bio->bi_iter.bi_sector = sector;
+ bio_set_dev(ctx->bio, iomap->bdev);
+ ctx->bio->bi_end_io = iomap_read_end_io;
+ }
+
+ bio_add_page(ctx->bio, page, plen, poff);
+done:
+ /*
+ * Move the caller beyond our range so that it keeps making progress.
+ * For that we have to include any leading non-uptodate ranges, but
+ * we can skip trailing ones as they will be handled in the next
+ * iteration.
+ */
+ return pos - orig_pos + plen;
+}
+
+int
+iomap_readpage(struct page *page, const struct iomap_ops *ops)
+{
+ struct iomap_readpage_ctx ctx = { .cur_page = page };
+ struct inode *inode = page->mapping->host;
+ unsigned poff;
+ loff_t ret;
+
+ for (poff = 0; poff < PAGE_SIZE; poff += ret) {
+ ret = iomap_apply(inode, page_offset(page) + poff,
+ PAGE_SIZE - poff, 0, ops, &ctx,
+ iomap_readpage_actor);
+ if (ret <= 0) {
+ WARN_ON_ONCE(ret == 0);
+ SetPageError(page);
+ break;
+ }
+ }
+
+ if (ctx.bio) {
+ submit_bio(ctx.bio);
+ WARN_ON_ONCE(!ctx.cur_page_in_bio);
+ } else {
+ WARN_ON_ONCE(ctx.cur_page_in_bio);
+ unlock_page(page);
+ }
+
+ /*
+ * Just like mpage_readpages and block_read_full_page we always
+ * return 0 and just mark the page as PageError on errors. This
+ * should be cleaned up all through the stack eventually.
+ */
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_readpage);
+
+static struct page *
+iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
+ loff_t length, loff_t *done)
+{
+ while (!list_empty(pages)) {
+ struct page *page = lru_to_page(pages);
+
+ if (page_offset(page) >= (u64)pos + length)
+ break;
+
+ list_del(&page->lru);
+ if (!add_to_page_cache_lru(page, inode->i_mapping, page->index,
+ GFP_NOFS))
+ return page;
+
+ /*
+ * If we already have a page in the page cache at index we are
+ * done. Upper layers don't care if it is uptodate after the
+ * readpages call itself as every page gets checked again once
+ * actually needed.
+ */
+ *done += PAGE_SIZE;
+ put_page(page);
+ }
+
+ return NULL;
+}
+
+static loff_t
+iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
+ void *data, struct iomap *iomap)
+{
+ struct iomap_readpage_ctx *ctx = data;
+ loff_t done, ret;
+
+ for (done = 0; done < length; done += ret) {
+ if (ctx->cur_page && offset_in_page(pos + done) == 0) {
+ if (!ctx->cur_page_in_bio)
+ unlock_page(ctx->cur_page);
+ put_page(ctx->cur_page);
+ ctx->cur_page = NULL;
+ }
+ if (!ctx->cur_page) {
+ ctx->cur_page = iomap_next_page(inode, ctx->pages,
+ pos, length, &done);
+ if (!ctx->cur_page)
+ break;
+ ctx->cur_page_in_bio = false;
+ }
+ ret = iomap_readpage_actor(inode, pos + done, length - done,
+ ctx, iomap);
+ }
+
+ return done;
+}
+
+int
+iomap_readpages(struct address_space *mapping, struct list_head *pages,
+ unsigned nr_pages, const struct iomap_ops *ops)
+{
+ struct iomap_readpage_ctx ctx = {
+ .pages = pages,
+ .is_readahead = true,
+ };
+ loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
+ loff_t last = page_offset(list_entry(pages->next, struct page, lru));
+ loff_t length = last - pos + PAGE_SIZE, ret = 0;
+
+ while (length > 0) {
+ ret = iomap_apply(mapping->host, pos, length, 0, ops,
+ &ctx, iomap_readpages_actor);
+ if (ret <= 0) {
+ WARN_ON_ONCE(ret == 0);
+ goto done;
+ }
+ pos += ret;
+ length -= ret;
+ }
+ ret = 0;
+done:
+ if (ctx.bio)
+ submit_bio(ctx.bio);
+ if (ctx.cur_page) {
+ if (!ctx.cur_page_in_bio)
+ unlock_page(ctx.cur_page);
+ put_page(ctx.cur_page);
+ }
+
+ /*
+ * Check that we didn't lose a page due to the arcance calling
+ * conventions..
+ */
+ WARN_ON_ONCE(!ret && !list_empty(ctx.pages));
+ return ret;
+}
+EXPORT_SYMBOL_GPL(iomap_readpages);
+
+/*
+ * iomap_is_partially_uptodate checks whether blocks within a page are
+ * uptodate or not.
+ *
+ * Returns true if all blocks which correspond to a file portion
+ * we want to read within the page are uptodate.
+ */
+int
+iomap_is_partially_uptodate(struct page *page, unsigned long from,
+ unsigned long count)
+{
+ struct iomap_page *iop = to_iomap_page(page);
+ struct inode *inode = page->mapping->host;
+ unsigned len, first, last;
+ unsigned i;
+
+ /* Limit range to one page */
+ len = min_t(unsigned, PAGE_SIZE - from, count);
+
+ /* First and last blocks in range within page */
+ first = from >> inode->i_blkbits;
+ last = (from + len - 1) >> inode->i_blkbits;
+
+ if (iop) {
+ for (i = first; i <= last; i++)
+ if (!test_bit(i, iop->uptodate))
+ return 0;
+ return 1;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
+
+int
+iomap_releasepage(struct page *page, gfp_t gfp_mask)
+{
+ /*
+ * mm accommodates an old ext3 case where clean pages might not have had
+ * the dirty bit cleared. Thus, it can send actual dirty pages to
+ * ->releasepage() via shrink_active_list(), skip those here.
+ */
+ if (PageDirty(page) || PageWriteback(page))
+ return 0;
+ iomap_page_release(page);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(iomap_releasepage);
+
+void
+iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
+{
+ /*
+ * If we are invalidating the entire page, clear the dirty state from it
+ * and release it to avoid unnecessary buildup of the LRU.
+ */
+ if (offset == 0 && len == PAGE_SIZE) {
+ WARN_ON_ONCE(PageWriteback(page));
+ cancel_dirty_page(page);
+ iomap_page_release(page);
+ }
+}
+EXPORT_SYMBOL_GPL(iomap_invalidatepage);
+
+#ifdef CONFIG_MIGRATION
+int
+iomap_migrate_page(struct address_space *mapping, struct page *newpage,
+ struct page *page, enum migrate_mode mode)
+{
+ int ret;
+
+ ret = migrate_page_move_mapping(mapping, newpage, page, mode, 0);
+ if (ret != MIGRATEPAGE_SUCCESS)
+ return ret;
+
+ if (page_has_private(page)) {
+ ClearPagePrivate(page);
+ get_page(newpage);
+ set_page_private(newpage, page_private(page));
+ set_page_private(page, 0);
+ put_page(page);
+ SetPagePrivate(newpage);
+ }
+
+ if (mode != MIGRATE_SYNC_NO_COPY)
+ migrate_page_copy(newpage, page);
+ else
+ migrate_page_states(newpage, page);
+ return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(iomap_migrate_page);
+#endif /* CONFIG_MIGRATION */
+
+static void
+iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
+{
+ loff_t i_size = i_size_read(inode);
+
+ /*
+ * Only truncate newly allocated pages beyoned EOF, even if the
+ * write started inside the existing inode size.
+ */
+ if (pos + len > i_size)
+ truncate_pagecache_range(inode, max(pos, i_size), pos + len);
+}
+
+static int
+iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page,
+ unsigned poff, unsigned plen, unsigned from, unsigned to,
+ struct iomap *iomap)
+{
+ struct bio_vec bvec;
+ struct bio bio;
+
+ if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) {
+ zero_user_segments(page, poff, from, to, poff + plen);
+ iomap_set_range_uptodate(page, poff, plen);
+ return 0;
+ }
+
+ bio_init(&bio, &bvec, 1);
+ bio.bi_opf = REQ_OP_READ;
+ bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
+ bio_set_dev(&bio, iomap->bdev);
+ __bio_add_page(&bio, page, plen, poff);
+ return submit_bio_wait(&bio);
+}
+
+static int
+__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
+ struct page *page, struct iomap *iomap)
+{
+ struct iomap_page *iop = iomap_page_create(inode, page);
+ loff_t block_size = i_blocksize(inode);
+ loff_t block_start = pos & ~(block_size - 1);
+ loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
+ unsigned from = offset_in_page(pos), to = from + len, poff, plen;
+ int status = 0;
+
+ if (PageUptodate(page))
+ return 0;
+
+ do {
+ iomap_adjust_read_range(inode, iop, &block_start,
+ block_end - block_start, &poff, &plen);
+ if (plen == 0)
+ break;
+
+ if ((from > poff && from < poff + plen) ||
+ (to > poff && to < poff + plen)) {
+ status = iomap_read_page_sync(inode, block_start, page,
+ poff, plen, from, to, iomap);
+ if (status)
+ break;
+ }
+
+ } while ((block_start += plen) < block_end);
+
+ return status;
+}
+
+static int
+iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, struct iomap *iomap)
+{
+ const struct iomap_page_ops *page_ops = iomap->page_ops;
+ pgoff_t index = pos >> PAGE_SHIFT;
+ struct page *page;
+ int status = 0;
+
+ BUG_ON(pos + len > iomap->offset + iomap->length);
+
+ if (fatal_signal_pending(current))
+ return -EINTR;
+
+ if (page_ops && page_ops->page_prepare) {
+ status = page_ops->page_prepare(inode, pos, len, iomap);
+ if (status)
+ return status;
+ }
+
+ page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
+ if (!page) {
+ status = -ENOMEM;
+ goto out_no_page;
+ }
+
+ if (iomap->type == IOMAP_INLINE)
+ iomap_read_inline_data(inode, page, iomap);
+ else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
+ status = __block_write_begin_int(page, pos, len, NULL, iomap);
+ else
+ status = __iomap_write_begin(inode, pos, len, page, iomap);
+
+ if (unlikely(status))
+ goto out_unlock;
+
+ *pagep = page;
+ return 0;
+
+out_unlock:
+ unlock_page(page);
+ put_page(page);
+ iomap_write_failed(inode, pos, len);
+
+out_no_page:
+ if (page_ops && page_ops->page_done)
+ page_ops->page_done(inode, pos, 0, NULL, iomap);
+ return status;
+}
+
+int
+iomap_set_page_dirty(struct page *page)
+{
+ struct address_space *mapping = page_mapping(page);
+ int newly_dirty;
+
+ if (unlikely(!mapping))
+ return !TestSetPageDirty(page);
+
+ /*
+ * Lock out page->mem_cgroup migration to keep PageDirty
+ * synchronized with per-memcg dirty page counters.
+ */
+ lock_page_memcg(page);
+ newly_dirty = !TestSetPageDirty(page);
+ if (newly_dirty)
+ __set_page_dirty(page, mapping, 0);
+ unlock_page_memcg(page);
+
+ if (newly_dirty)
+ __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+ return newly_dirty;
+}
+EXPORT_SYMBOL_GPL(iomap_set_page_dirty);
+
+static int
+__iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
+ unsigned copied, struct page *page, struct iomap *iomap)
+{
+ flush_dcache_page(page);
+
+ /*
+ * The blocks that were entirely written will now be uptodate, so we
+ * don't have to worry about a readpage reading them and overwriting a
+ * partial write. However if we have encountered a short write and only
+ * partially written into a block, it will not be marked uptodate, so a
+ * readpage might come in and destroy our partial write.
+ *
+ * Do the simplest thing, and just treat any short write to a non
+ * uptodate page as a zero-length write, and force the caller to redo
+ * the whole thing.
+ */
+ if (unlikely(copied < len && !PageUptodate(page)))
+ return 0;
+ iomap_set_range_uptodate(page, offset_in_page(pos), len);
+ iomap_set_page_dirty(page);
+ return copied;
+}
+
+static int
+iomap_write_end_inline(struct inode *inode, struct page *page,
+ struct iomap *iomap, loff_t pos, unsigned copied)
+{
+ void *addr;
+
+ WARN_ON_ONCE(!PageUptodate(page));
+ BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
+
+ addr = kmap_atomic(page);
+ memcpy(iomap->inline_data + pos, addr + pos, copied);
+ kunmap_atomic(addr);
+
+ mark_inode_dirty(inode);
+ return copied;
+}
+
+static int
+iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
+ unsigned copied, struct page *page, struct iomap *iomap)
+{
+ const struct iomap_page_ops *page_ops = iomap->page_ops;
+ loff_t old_size = inode->i_size;
+ int ret;
+
+ if (iomap->type == IOMAP_INLINE) {
+ ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
+ } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
+ ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
+ page, NULL);
+ } else {
+ ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
+ }
+
+ /*
+ * Update the in-memory inode size after copying the data into the page
+ * cache. It's up to the file system to write the updated size to disk,
+ * preferably after I/O completion so that no stale data is exposed.
+ */
+ if (pos + ret > old_size) {
+ i_size_write(inode, pos + ret);
+ iomap->flags |= IOMAP_F_SIZE_CHANGED;
+ }
+ unlock_page(page);
+
+ if (old_size < pos)
+ pagecache_isize_extended(inode, old_size, pos);
+ if (page_ops && page_ops->page_done)
+ page_ops->page_done(inode, pos, ret, page, iomap);
+ put_page(page);
+
+ if (ret < len)
+ iomap_write_failed(inode, pos, len);
+ return ret;
+}
+
+static loff_t
+iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
+ struct iomap *iomap)
+{
+ struct iov_iter *i = data;
+ long status = 0;
+ ssize_t written = 0;
+ unsigned int flags = AOP_FLAG_NOFS;
+
+ do {
+ struct page *page;
+ unsigned long offset; /* Offset into pagecache page */
+ unsigned long bytes; /* Bytes to write to page */
+ size_t copied; /* Bytes copied from user */
+
+ offset = offset_in_page(pos);
+ bytes = min_t(unsigned long, PAGE_SIZE - offset,
+ iov_iter_count(i));
+again:
+ if (bytes > length)
+ bytes = length;
+
+ /*
+ * Bring in the user page that we will copy from _first_.
+ * Otherwise there's a nasty deadlock on copying from the
+ * same page as we're writing to, without it being marked
+ * up-to-date.
+ *
+ * Not only is this an optimisation, but it is also required
+ * to check that the address is actually valid, when atomic
+ * usercopies are used, below.
+ */
+ if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
+ status = -EFAULT;
+ break;
+ }
+
+ status = iomap_write_begin(inode, pos, bytes, flags, &page,
+ iomap);
+ if (unlikely(status))
+ break;
+
+ if (mapping_writably_mapped(inode->i_mapping))
+ flush_dcache_page(page);
+
+ copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
+
+ flush_dcache_page(page);
+
+ status = iomap_write_end(inode, pos, bytes, copied, page,
+ iomap);
+ if (unlikely(status < 0))
+ break;
+ copied = status;
+
+ cond_resched();
+
+ iov_iter_advance(i, copied);
+ if (unlikely(copied == 0)) {
+ /*
+ * If we were unable to copy any data at all, we must
+ * fall back to a single segment length write.
+ *
+ * If we didn't fallback here, we could livelock
+ * because not all segments in the iov can be copied at
+ * once without a pagefault.
+ */
+ bytes = min_t(unsigned long, PAGE_SIZE - offset,
+ iov_iter_single_seg_count(i));
+ goto again;
+ }
+ pos += copied;
+ written += copied;
+ length -= copied;
+
+ balance_dirty_pages_ratelimited(inode->i_mapping);
+ } while (iov_iter_count(i) && length);
+
+ return written ? written : status;
+}
+
+ssize_t
+iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
+ const struct iomap_ops *ops)
+{
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ loff_t pos = iocb->ki_pos, ret = 0, written = 0;
+
+ while (iov_iter_count(iter)) {
+ ret = iomap_apply(inode, pos, iov_iter_count(iter),
+ IOMAP_WRITE, ops, iter, iomap_write_actor);
+ if (ret <= 0)
+ break;
+ pos += ret;
+ written += ret;
+ }
+
+ return written ? written : ret;
+}
+EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
+
+static struct page *
+__iomap_read_page(struct inode *inode, loff_t offset)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page;
+
+ page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
+ if (IS_ERR(page))
+ return page;
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-EIO);
+ }
+ return page;
+}
+
+static loff_t
+iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
+ struct iomap *iomap)
+{
+ long status = 0;
+ ssize_t written = 0;
+
+ do {
+ struct page *page, *rpage;
+ unsigned long offset; /* Offset into pagecache page */
+ unsigned long bytes; /* Bytes to write to page */
+
+ offset = offset_in_page(pos);
+ bytes = min_t(loff_t, PAGE_SIZE - offset, length);
+
+ rpage = __iomap_read_page(inode, pos);
+ if (IS_ERR(rpage))
+ return PTR_ERR(rpage);
+
+ status = iomap_write_begin(inode, pos, bytes,
+ AOP_FLAG_NOFS, &page, iomap);
+ put_page(rpage);
+ if (unlikely(status))
+ return status;
+
+ WARN_ON_ONCE(!PageUptodate(page));
+
+ status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
+ if (unlikely(status <= 0)) {
+ if (WARN_ON_ONCE(status == 0))
+ return -EIO;
+ return status;
+ }
+
+ cond_resched();
+
+ pos += status;
+ written += status;
+ length -= status;
+
+ balance_dirty_pages_ratelimited(inode->i_mapping);
+ } while (length);
+
+ return written;
+}
+
+int
+iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
+ const struct iomap_ops *ops)
+{
+ loff_t ret;
+
+ while (len) {
+ ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
+ iomap_dirty_actor);
+ if (ret <= 0)
+ return ret;
+ pos += ret;
+ len -= ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_file_dirty);
+
+static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
+ unsigned bytes, struct iomap *iomap)
+{
+ struct page *page;
+ int status;
+
+ status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page,
+ iomap);
+ if (status)
+ return status;
+
+ zero_user(page, offset, bytes);
+ mark_page_accessed(page);
+
+ return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
+}
+
+static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
+ struct iomap *iomap)
+{
+ return __dax_zero_page_range(iomap->bdev, iomap->dax_dev,
+ iomap_sector(iomap, pos & PAGE_MASK), offset, bytes);
+}
+
+static loff_t
+iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
+ void *data, struct iomap *iomap)
+{
+ bool *did_zero = data;
+ loff_t written = 0;
+ int status;
+
+ /* already zeroed? we're done. */
+ if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
+ return count;
+
+ do {
+ unsigned offset, bytes;
+
+ offset = offset_in_page(pos);
+ bytes = min_t(loff_t, PAGE_SIZE - offset, count);
+
+ if (IS_DAX(inode))
+ status = iomap_dax_zero(pos, offset, bytes, iomap);
+ else
+ status = iomap_zero(inode, pos, offset, bytes, iomap);
+ if (status < 0)
+ return status;
+
+ pos += bytes;
+ count -= bytes;
+ written += bytes;
+ if (did_zero)
+ *did_zero = true;
+ } while (count > 0);
+
+ return written;
+}
+
+int
+iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
+ const struct iomap_ops *ops)
+{
+ loff_t ret;
+
+ while (len > 0) {
+ ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
+ ops, did_zero, iomap_zero_range_actor);
+ if (ret <= 0)
+ return ret;
+
+ pos += ret;
+ len -= ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_zero_range);
+
+int
+iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
+ const struct iomap_ops *ops)
+{
+ unsigned int blocksize = i_blocksize(inode);
+ unsigned int off = pos & (blocksize - 1);
+
+ /* Block boundary? Nothing to do */
+ if (!off)
+ return 0;
+ return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
+}
+EXPORT_SYMBOL_GPL(iomap_truncate_page);
+
+static loff_t
+iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
+ void *data, struct iomap *iomap)
+{
+ struct page *page = data;
+ int ret;
+
+ if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
+ ret = __block_write_begin_int(page, pos, length, NULL, iomap);
+ if (ret)
+ return ret;
+ block_commit_write(page, 0, length);
+ } else {
+ WARN_ON_ONCE(!PageUptodate(page));
+ iomap_page_create(inode, page);
+ set_page_dirty(page);
+ }
+
+ return length;
+}
+
+vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
+{
+ struct page *page = vmf->page;
+ struct inode *inode = file_inode(vmf->vma->vm_file);
+ unsigned long length;
+ loff_t offset, size;
+ ssize_t ret;
+
+ lock_page(page);
+ size = i_size_read(inode);
+ if ((page->mapping != inode->i_mapping) ||
+ (page_offset(page) > size)) {
+ /* We overload EFAULT to mean page got truncated */
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+
+ /* page is wholly or partially inside EOF */
+ if (((page->index + 1) << PAGE_SHIFT) > size)
+ length = offset_in_page(size);
+ else
+ length = PAGE_SIZE;
+
+ offset = page_offset(page);
+ while (length > 0) {
+ ret = iomap_apply(inode, offset, length,
+ IOMAP_WRITE | IOMAP_FAULT, ops, page,
+ iomap_page_mkwrite_actor);
+ if (unlikely(ret <= 0))
+ goto out_unlock;
+ offset += ret;
+ length -= ret;
+ }
+
+ wait_for_stable_page(page);
+ return VM_FAULT_LOCKED;
+out_unlock:
+ unlock_page(page);
+ return block_page_mkwrite_return(ret);
+}
+EXPORT_SYMBOL_GPL(iomap_page_mkwrite);

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