blob: aa7f8148cd0d06ff0707308e7f49632e3306eac1 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/bio.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/page-flags.h>
#include <linux/sched/mm.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/swap.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include <linux/prefetch.h>
#include <linux/fsverity.h>
#include "extent_io.h"
#include "extent-io-tree.h"
#include "extent_map.h"
#include "ctree.h"
#include "btrfs_inode.h"
#include "bio.h"
#include "locking.h"
#include "backref.h"
#include "disk-io.h"
#include "subpage.h"
#include "zoned.h"
#include "block-group.h"
#include "compression.h"
#include "fs.h"
#include "accessors.h"
#include "file-item.h"
#include "file.h"
#include "dev-replace.h"
#include "super.h"
#include "transaction.h"
static struct kmem_cache *extent_buffer_cache;
#ifdef CONFIG_BTRFS_DEBUG
static inline void btrfs_leak_debug_add_eb(struct extent_buffer *eb)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
unsigned long flags;
spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
list_add(&eb->leak_list, &fs_info->allocated_ebs);
spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags);
}
static inline void btrfs_leak_debug_del_eb(struct extent_buffer *eb)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
unsigned long flags;
spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
list_del(&eb->leak_list);
spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags);
}
void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info)
{
struct extent_buffer *eb;
unsigned long flags;
/*
* If we didn't get into open_ctree our allocated_ebs will not be
* initialized, so just skip this.
*/
if (!fs_info->allocated_ebs.next)
return;
WARN_ON(!list_empty(&fs_info->allocated_ebs));
spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
while (!list_empty(&fs_info->allocated_ebs)) {
eb = list_first_entry(&fs_info->allocated_ebs,
struct extent_buffer, leak_list);
pr_err(
"BTRFS: buffer leak start %llu len %u refs %d bflags %lu owner %llu\n",
eb->start, eb->len, atomic_read(&eb->refs), eb->bflags,
btrfs_header_owner(eb));
list_del(&eb->leak_list);
WARN_ON_ONCE(1);
kmem_cache_free(extent_buffer_cache, eb);
}
spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags);
}
#else
#define btrfs_leak_debug_add_eb(eb) do {} while (0)
#define btrfs_leak_debug_del_eb(eb) do {} while (0)
#endif
/*
* Structure to record info about the bio being assembled, and other info like
* how many bytes are there before stripe/ordered extent boundary.
*/
struct btrfs_bio_ctrl {
struct btrfs_bio *bbio;
enum btrfs_compression_type compress_type;
u32 len_to_oe_boundary;
blk_opf_t opf;
btrfs_bio_end_io_t end_io_func;
struct writeback_control *wbc;
};
static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
{
struct btrfs_bio *bbio = bio_ctrl->bbio;
if (!bbio)
return;
/* Caller should ensure the bio has at least some range added */
ASSERT(bbio->bio.bi_iter.bi_size);
if (btrfs_op(&bbio->bio) == BTRFS_MAP_READ &&
bio_ctrl->compress_type != BTRFS_COMPRESS_NONE)
btrfs_submit_compressed_read(bbio);
else
btrfs_submit_bio(bbio, 0);
/* The bbio is owned by the end_io handler now */
bio_ctrl->bbio = NULL;
}
/*
* Submit or fail the current bio in the bio_ctrl structure.
*/
static void submit_write_bio(struct btrfs_bio_ctrl *bio_ctrl, int ret)
{
struct btrfs_bio *bbio = bio_ctrl->bbio;
if (!bbio)
return;
if (ret) {
ASSERT(ret < 0);
btrfs_bio_end_io(bbio, errno_to_blk_status(ret));
/* The bio is owned by the end_io handler now */
bio_ctrl->bbio = NULL;
} else {
submit_one_bio(bio_ctrl);
}
}
int __init extent_buffer_init_cachep(void)
{
extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
sizeof(struct extent_buffer), 0, 0,
NULL);
if (!extent_buffer_cache)
return -ENOMEM;
return 0;
}
void __cold extent_buffer_free_cachep(void)
{
/*
* Make sure all delayed rcu free are flushed before we
* destroy caches.
*/
rcu_barrier();
kmem_cache_destroy(extent_buffer_cache);
}
static void process_one_page(struct btrfs_fs_info *fs_info,
struct page *page, const struct page *locked_page,
unsigned long page_ops, u64 start, u64 end)
{
struct folio *folio = page_folio(page);
u32 len;
ASSERT(end + 1 - start != 0 && end + 1 - start < U32_MAX);
len = end + 1 - start;
if (page_ops & PAGE_SET_ORDERED)
btrfs_folio_clamp_set_ordered(fs_info, folio, start, len);
if (page_ops & PAGE_START_WRITEBACK) {
btrfs_folio_clamp_clear_dirty(fs_info, folio, start, len);
btrfs_folio_clamp_set_writeback(fs_info, folio, start, len);
}
if (page_ops & PAGE_END_WRITEBACK)
btrfs_folio_clamp_clear_writeback(fs_info, folio, start, len);
if (page != locked_page && (page_ops & PAGE_UNLOCK))
btrfs_folio_end_writer_lock(fs_info, folio, start, len);
}
static void __process_pages_contig(struct address_space *mapping,
const struct page *locked_page, u64 start, u64 end,
unsigned long page_ops)
{
struct btrfs_fs_info *fs_info = inode_to_fs_info(mapping->host);
pgoff_t start_index = start >> PAGE_SHIFT;
pgoff_t end_index = end >> PAGE_SHIFT;
pgoff_t index = start_index;
struct folio_batch fbatch;
int i;
folio_batch_init(&fbatch);
while (index <= end_index) {
int found_folios;
found_folios = filemap_get_folios_contig(mapping, &index,
end_index, &fbatch);
for (i = 0; i < found_folios; i++) {
struct folio *folio = fbatch.folios[i];
process_one_page(fs_info, &folio->page, locked_page,
page_ops, start, end);
}
folio_batch_release(&fbatch);
cond_resched();
}
}
static noinline void __unlock_for_delalloc(const struct inode *inode,
const struct page *locked_page,
u64 start, u64 end)
{
unsigned long index = start >> PAGE_SHIFT;
unsigned long end_index = end >> PAGE_SHIFT;
ASSERT(locked_page);
if (index == locked_page->index && end_index == index)
return;
__process_pages_contig(inode->i_mapping, locked_page, start, end,
PAGE_UNLOCK);
}
static noinline int lock_delalloc_pages(struct inode *inode,
const struct page *locked_page,
u64 start,
u64 end)
{
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
struct address_space *mapping = inode->i_mapping;
pgoff_t start_index = start >> PAGE_SHIFT;
pgoff_t end_index = end >> PAGE_SHIFT;
pgoff_t index = start_index;
u64 processed_end = start;
struct folio_batch fbatch;
if (index == locked_page->index && index == end_index)
return 0;
folio_batch_init(&fbatch);
while (index <= end_index) {
unsigned int found_folios, i;
found_folios = filemap_get_folios_contig(mapping, &index,
end_index, &fbatch);
if (found_folios == 0)
goto out;
for (i = 0; i < found_folios; i++) {
struct folio *folio = fbatch.folios[i];
struct page *page = folio_page(folio, 0);
u32 len = end + 1 - start;
if (page == locked_page)
continue;
if (btrfs_folio_start_writer_lock(fs_info, folio, start,
len))
goto out;
if (!PageDirty(page) || page->mapping != mapping) {
btrfs_folio_end_writer_lock(fs_info, folio, start,
len);
goto out;
}
processed_end = page_offset(page) + PAGE_SIZE - 1;
}
folio_batch_release(&fbatch);
cond_resched();
}
return 0;
out:
folio_batch_release(&fbatch);
if (processed_end > start)
__unlock_for_delalloc(inode, locked_page, start, processed_end);
return -EAGAIN;
}
/*
* Find and lock a contiguous range of bytes in the file marked as delalloc, no
* more than @max_bytes.
*
* @start: The original start bytenr to search.
* Will store the extent range start bytenr.
* @end: The original end bytenr of the search range
* Will store the extent range end bytenr.
*
* Return true if we find a delalloc range which starts inside the original
* range, and @start/@end will store the delalloc range start/end.
*
* Return false if we can't find any delalloc range which starts inside the
* original range, and @start/@end will be the non-delalloc range start/end.
*/
EXPORT_FOR_TESTS
noinline_for_stack bool find_lock_delalloc_range(struct inode *inode,
struct page *locked_page, u64 *start,
u64 *end)
{
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
const u64 orig_start = *start;
const u64 orig_end = *end;
/* The sanity tests may not set a valid fs_info. */
u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE;
u64 delalloc_start;
u64 delalloc_end;
bool found;
struct extent_state *cached_state = NULL;
int ret;
int loops = 0;
/* Caller should pass a valid @end to indicate the search range end */
ASSERT(orig_end > orig_start);
/* The range should at least cover part of the page */
ASSERT(!(orig_start >= page_offset(locked_page) + PAGE_SIZE ||
orig_end <= page_offset(locked_page)));
again:
/* step one, find a bunch of delalloc bytes starting at start */
delalloc_start = *start;
delalloc_end = 0;
found = btrfs_find_delalloc_range(tree, &delalloc_start, &delalloc_end,
max_bytes, &cached_state);
if (!found || delalloc_end <= *start || delalloc_start > orig_end) {
*start = delalloc_start;
/* @delalloc_end can be -1, never go beyond @orig_end */
*end = min(delalloc_end, orig_end);
free_extent_state(cached_state);
return false;
}
/*
* start comes from the offset of locked_page. We have to lock
* pages in order, so we can't process delalloc bytes before
* locked_page
*/
if (delalloc_start < *start)
delalloc_start = *start;
/*
* make sure to limit the number of pages we try to lock down
*/
if (delalloc_end + 1 - delalloc_start > max_bytes)
delalloc_end = delalloc_start + max_bytes - 1;
/* step two, lock all the pages after the page that has start */
ret = lock_delalloc_pages(inode, locked_page,
delalloc_start, delalloc_end);
ASSERT(!ret || ret == -EAGAIN);
if (ret == -EAGAIN) {
/* some of the pages are gone, lets avoid looping by
* shortening the size of the delalloc range we're searching
*/
free_extent_state(cached_state);
cached_state = NULL;
if (!loops) {
max_bytes = PAGE_SIZE;
loops = 1;
goto again;
} else {
found = false;
goto out_failed;
}
}
/* step three, lock the state bits for the whole range */
lock_extent(tree, delalloc_start, delalloc_end, &cached_state);
/* then test to make sure it is all still delalloc */
ret = test_range_bit(tree, delalloc_start, delalloc_end,
EXTENT_DELALLOC, cached_state);
unlock_extent(tree, delalloc_start, delalloc_end, &cached_state);
if (!ret) {
__unlock_for_delalloc(inode, locked_page,
delalloc_start, delalloc_end);
cond_resched();
goto again;
}
*start = delalloc_start;
*end = delalloc_end;
out_failed:
return found;
}
void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
const struct page *locked_page,
struct extent_state **cached,
u32 clear_bits, unsigned long page_ops)
{
clear_extent_bit(&inode->io_tree, start, end, clear_bits, cached);
__process_pages_contig(inode->vfs_inode.i_mapping, locked_page,
start, end, page_ops);
}
static bool btrfs_verify_page(struct page *page, u64 start)
{
if (!fsverity_active(page->mapping->host) ||
PageUptodate(page) ||
start >= i_size_read(page->mapping->host))
return true;
return fsverity_verify_page(page);
}
static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len)
{
struct btrfs_fs_info *fs_info = page_to_fs_info(page);
struct folio *folio = page_folio(page);
ASSERT(page_offset(page) <= start &&
start + len <= page_offset(page) + PAGE_SIZE);
if (uptodate && btrfs_verify_page(page, start))
btrfs_folio_set_uptodate(fs_info, folio, start, len);
else
btrfs_folio_clear_uptodate(fs_info, folio, start, len);
if (!btrfs_is_subpage(fs_info, page->mapping))
unlock_page(page);
else
btrfs_subpage_end_reader(fs_info, folio, start, len);
}
/*
* After a write IO is done, we need to:
*
* - clear the uptodate bits on error
* - clear the writeback bits in the extent tree for the range
* - filio_end_writeback() if there is no more pending io for the folio
*
* Scheduling is not allowed, so the extent state tree is expected
* to have one and only one object corresponding to this IO.
*/
static void end_bbio_data_write(struct btrfs_bio *bbio)
{
struct btrfs_fs_info *fs_info = bbio->fs_info;
struct bio *bio = &bbio->bio;
int error = blk_status_to_errno(bio->bi_status);
struct folio_iter fi;
const u32 sectorsize = fs_info->sectorsize;
ASSERT(!bio_flagged(bio, BIO_CLONED));
bio_for_each_folio_all(fi, bio) {
struct folio *folio = fi.folio;
u64 start = folio_pos(folio) + fi.offset;
u32 len = fi.length;
/* Only order 0 (single page) folios are allowed for data. */
ASSERT(folio_order(folio) == 0);
/* Our read/write should always be sector aligned. */
if (!IS_ALIGNED(fi.offset, sectorsize))
btrfs_err(fs_info,
"partial page write in btrfs with offset %zu and length %zu",
fi.offset, fi.length);
else if (!IS_ALIGNED(fi.length, sectorsize))
btrfs_info(fs_info,
"incomplete page write with offset %zu and length %zu",
fi.offset, fi.length);
btrfs_finish_ordered_extent(bbio->ordered,
folio_page(folio, 0), start, len, !error);
if (error)
mapping_set_error(folio->mapping, error);
btrfs_folio_clear_writeback(fs_info, folio, start, len);
}
bio_put(bio);
}
/*
* Record previously processed extent range
*
* For endio_readpage_release_extent() to handle a full extent range, reducing
* the extent io operations.
*/
struct processed_extent {
struct btrfs_inode *inode;
/* Start of the range in @inode */
u64 start;
/* End of the range in @inode */
u64 end;
bool uptodate;
};
/*
* Try to release processed extent range
*
* May not release the extent range right now if the current range is
* contiguous to processed extent.
*
* Will release processed extent when any of @inode, @uptodate, the range is
* no longer contiguous to the processed range.
*
* Passing @inode == NULL will force processed extent to be released.
*/
static void endio_readpage_release_extent(struct processed_extent *processed,
struct btrfs_inode *inode, u64 start, u64 end,
bool uptodate)
{
struct extent_state *cached = NULL;
struct extent_io_tree *tree;
/* The first extent, initialize @processed */
if (!processed->inode)
goto update;
/*
* Contiguous to processed extent, just uptodate the end.
*
* Several things to notice:
*
* - bio can be merged as long as on-disk bytenr is contiguous
* This means we can have page belonging to other inodes, thus need to
* check if the inode still matches.
* - bvec can contain range beyond current page for multi-page bvec
* Thus we need to do processed->end + 1 >= start check
*/
if (processed->inode == inode && processed->uptodate == uptodate &&
processed->end + 1 >= start && end >= processed->end) {
processed->end = end;
return;
}
tree = &processed->inode->io_tree;
/*
* Now we don't have range contiguous to the processed range, release
* the processed range now.
*/
unlock_extent(tree, processed->start, processed->end, &cached);
update:
/* Update processed to current range */
processed->inode = inode;
processed->start = start;
processed->end = end;
processed->uptodate = uptodate;
}
static void begin_page_read(struct btrfs_fs_info *fs_info, struct page *page)
{
struct folio *folio = page_folio(page);
ASSERT(folio_test_locked(folio));
if (!btrfs_is_subpage(fs_info, folio->mapping))
return;
ASSERT(folio_test_private(folio));
btrfs_subpage_start_reader(fs_info, folio, page_offset(page), PAGE_SIZE);
}
/*
* After a data read IO is done, we need to:
*
* - clear the uptodate bits on error
* - set the uptodate bits if things worked
* - set the folio up to date if all extents in the tree are uptodate
* - clear the lock bit in the extent tree
* - unlock the folio if there are no other extents locked for it
*
* Scheduling is not allowed, so the extent state tree is expected
* to have one and only one object corresponding to this IO.
*/
static void end_bbio_data_read(struct btrfs_bio *bbio)
{
struct btrfs_fs_info *fs_info = bbio->fs_info;
struct bio *bio = &bbio->bio;
struct processed_extent processed = { 0 };
struct folio_iter fi;
const u32 sectorsize = fs_info->sectorsize;
ASSERT(!bio_flagged(bio, BIO_CLONED));
bio_for_each_folio_all(fi, &bbio->bio) {
bool uptodate = !bio->bi_status;
struct folio *folio = fi.folio;
struct inode *inode = folio->mapping->host;
u64 start;
u64 end;
u32 len;
/* For now only order 0 folios are supported for data. */
ASSERT(folio_order(folio) == 0);
btrfs_debug(fs_info,
"%s: bi_sector=%llu, err=%d, mirror=%u",
__func__, bio->bi_iter.bi_sector, bio->bi_status,
bbio->mirror_num);
/*
* We always issue full-sector reads, but if some block in a
* folio fails to read, blk_update_request() will advance
* bv_offset and adjust bv_len to compensate. Print a warning
* for unaligned offsets, and an error if they don't add up to
* a full sector.
*/
if (!IS_ALIGNED(fi.offset, sectorsize))
btrfs_err(fs_info,
"partial page read in btrfs with offset %zu and length %zu",
fi.offset, fi.length);
else if (!IS_ALIGNED(fi.offset + fi.length, sectorsize))
btrfs_info(fs_info,
"incomplete page read with offset %zu and length %zu",
fi.offset, fi.length);
start = folio_pos(folio) + fi.offset;
end = start + fi.length - 1;
len = fi.length;
if (likely(uptodate)) {
loff_t i_size = i_size_read(inode);
pgoff_t end_index = i_size >> folio_shift(folio);
/*
* Zero out the remaining part if this range straddles
* i_size.
*
* Here we should only zero the range inside the folio,
* not touch anything else.
*
* NOTE: i_size is exclusive while end is inclusive.
*/
if (folio_index(folio) == end_index && i_size <= end) {
u32 zero_start = max(offset_in_folio(folio, i_size),
offset_in_folio(folio, start));
u32 zero_len = offset_in_folio(folio, end) + 1 -
zero_start;
folio_zero_range(folio, zero_start, zero_len);
}
}
/* Update page status and unlock. */
end_page_read(folio_page(folio, 0), uptodate, start, len);
endio_readpage_release_extent(&processed, BTRFS_I(inode),
start, end, uptodate);
}
/* Release the last extent */
endio_readpage_release_extent(&processed, NULL, 0, 0, false);
bio_put(bio);
}
/*
* Populate every free slot in a provided array with folios using GFP_NOFS.
*
* @nr_folios: number of folios to allocate
* @folio_array: the array to fill with folios; any existing non-NULL entries in
* the array will be skipped
*
* Return: 0 if all folios were able to be allocated;
* -ENOMEM otherwise, the partially allocated folios would be freed and
* the array slots zeroed
*/
int btrfs_alloc_folio_array(unsigned int nr_folios, struct folio **folio_array)
{
for (int i = 0; i < nr_folios; i++) {
if (folio_array[i])
continue;
folio_array[i] = folio_alloc(GFP_NOFS, 0);
if (!folio_array[i])
goto error;
}
return 0;
error:
for (int i = 0; i < nr_folios; i++) {
if (folio_array[i])
folio_put(folio_array[i]);
}
return -ENOMEM;
}
/*
* Populate every free slot in a provided array with pages, using GFP_NOFS.
*
* @nr_pages: number of pages to allocate
* @page_array: the array to fill with pages; any existing non-null entries in
* the array will be skipped
* @nofail: whether using __GFP_NOFAIL flag
*
* Return: 0 if all pages were able to be allocated;
* -ENOMEM otherwise, the partially allocated pages would be freed and
* the array slots zeroed
*/
int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array,
bool nofail)
{
const gfp_t gfp = nofail ? (GFP_NOFS | __GFP_NOFAIL) : GFP_NOFS;
unsigned int allocated;
for (allocated = 0; allocated < nr_pages;) {
unsigned int last = allocated;
allocated = alloc_pages_bulk_array(gfp, nr_pages, page_array);
if (unlikely(allocated == last)) {
/* No progress, fail and do cleanup. */
for (int i = 0; i < allocated; i++) {
__free_page(page_array[i]);
page_array[i] = NULL;
}
return -ENOMEM;
}
}
return 0;
}
/*
* Populate needed folios for the extent buffer.
*
* For now, the folios populated are always in order 0 (aka, single page).
*/
static int alloc_eb_folio_array(struct extent_buffer *eb, bool nofail)
{
struct page *page_array[INLINE_EXTENT_BUFFER_PAGES] = { 0 };
int num_pages = num_extent_pages(eb);
int ret;
ret = btrfs_alloc_page_array(num_pages, page_array, nofail);
if (ret < 0)
return ret;
for (int i = 0; i < num_pages; i++)
eb->folios[i] = page_folio(page_array[i]);
eb->folio_size = PAGE_SIZE;
eb->folio_shift = PAGE_SHIFT;
return 0;
}
static bool btrfs_bio_is_contig(struct btrfs_bio_ctrl *bio_ctrl,
struct page *page, u64 disk_bytenr,
unsigned int pg_offset)
{
struct bio *bio = &bio_ctrl->bbio->bio;
struct bio_vec *bvec = bio_last_bvec_all(bio);
const sector_t sector = disk_bytenr >> SECTOR_SHIFT;
if (bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) {
/*
* For compression, all IO should have its logical bytenr set
* to the starting bytenr of the compressed extent.
*/
return bio->bi_iter.bi_sector == sector;
}
/*
* The contig check requires the following conditions to be met:
*
* 1) The pages are belonging to the same inode
* This is implied by the call chain.
*
* 2) The range has adjacent logical bytenr
*
* 3) The range has adjacent file offset
* This is required for the usage of btrfs_bio->file_offset.
*/
return bio_end_sector(bio) == sector &&
page_offset(bvec->bv_page) + bvec->bv_offset + bvec->bv_len ==
page_offset(page) + pg_offset;
}
static void alloc_new_bio(struct btrfs_inode *inode,
struct btrfs_bio_ctrl *bio_ctrl,
u64 disk_bytenr, u64 file_offset)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct btrfs_bio *bbio;
bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, fs_info,
bio_ctrl->end_io_func, NULL);
bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
bbio->inode = inode;
bbio->file_offset = file_offset;
bio_ctrl->bbio = bbio;
bio_ctrl->len_to_oe_boundary = U32_MAX;
/* Limit data write bios to the ordered boundary. */
if (bio_ctrl->wbc) {
struct btrfs_ordered_extent *ordered;
ordered = btrfs_lookup_ordered_extent(inode, file_offset);
if (ordered) {
bio_ctrl->len_to_oe_boundary = min_t(u32, U32_MAX,
ordered->file_offset +
ordered->disk_num_bytes - file_offset);
bbio->ordered = ordered;
}
/*
* Pick the last added device to support cgroup writeback. For
* multi-device file systems this means blk-cgroup policies have
* to always be set on the last added/replaced device.
* This is a bit odd but has been like that for a long time.
*/
bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev);
wbc_init_bio(bio_ctrl->wbc, &bbio->bio);
}
}
/*
* @disk_bytenr: logical bytenr where the write will be
* @page: page to add to the bio
* @size: portion of page that we want to write to
* @pg_offset: offset of the new bio or to check whether we are adding
* a contiguous page to the previous one
*
* The will either add the page into the existing @bio_ctrl->bbio, or allocate a
* new one in @bio_ctrl->bbio.
* The mirror number for this IO should already be initizlied in
* @bio_ctrl->mirror_num.
*/
static void submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl,
u64 disk_bytenr, struct page *page,
size_t size, unsigned long pg_offset)
{
struct btrfs_inode *inode = page_to_inode(page);
ASSERT(pg_offset + size <= PAGE_SIZE);
ASSERT(bio_ctrl->end_io_func);
if (bio_ctrl->bbio &&
!btrfs_bio_is_contig(bio_ctrl, page, disk_bytenr, pg_offset))
submit_one_bio(bio_ctrl);
do {
u32 len = size;
/* Allocate new bio if needed */
if (!bio_ctrl->bbio) {
alloc_new_bio(inode, bio_ctrl, disk_bytenr,
page_offset(page) + pg_offset);
}
/* Cap to the current ordered extent boundary if there is one. */
if (len > bio_ctrl->len_to_oe_boundary) {
ASSERT(bio_ctrl->compress_type == BTRFS_COMPRESS_NONE);
ASSERT(is_data_inode(inode));
len = bio_ctrl->len_to_oe_boundary;
}
if (bio_add_page(&bio_ctrl->bbio->bio, page, len, pg_offset) != len) {
/* bio full: move on to a new one */
submit_one_bio(bio_ctrl);
continue;
}
if (bio_ctrl->wbc)
wbc_account_cgroup_owner(bio_ctrl->wbc, page, len);
size -= len;
pg_offset += len;
disk_bytenr += len;
/*
* len_to_oe_boundary defaults to U32_MAX, which isn't page or
* sector aligned. alloc_new_bio() then sets it to the end of
* our ordered extent for writes into zoned devices.
*
* When len_to_oe_boundary is tracking an ordered extent, we
* trust the ordered extent code to align things properly, and
* the check above to cap our write to the ordered extent
* boundary is correct.
*
* When len_to_oe_boundary is U32_MAX, the cap above would
* result in a 4095 byte IO for the last page right before
* we hit the bio limit of UINT_MAX. bio_add_page() has all
* the checks required to make sure we don't overflow the bio,
* and we should just ignore len_to_oe_boundary completely
* unless we're using it to track an ordered extent.
*
* It's pretty hard to make a bio sized U32_MAX, but it can
* happen when the page cache is able to feed us contiguous
* pages for large extents.
*/
if (bio_ctrl->len_to_oe_boundary != U32_MAX)
bio_ctrl->len_to_oe_boundary -= len;
/* Ordered extent boundary: move on to a new bio. */
if (bio_ctrl->len_to_oe_boundary == 0)
submit_one_bio(bio_ctrl);
} while (size);
}
static int attach_extent_buffer_folio(struct extent_buffer *eb,
struct folio *folio,
struct btrfs_subpage *prealloc)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
int ret = 0;
/*
* If the page is mapped to btree inode, we should hold the private
* lock to prevent race.
* For cloned or dummy extent buffers, their pages are not mapped and
* will not race with any other ebs.
*/
if (folio->mapping)
lockdep_assert_held(&folio->mapping->i_private_lock);
if (fs_info->nodesize >= PAGE_SIZE) {
if (!folio_test_private(folio))
folio_attach_private(folio, eb);
else
WARN_ON(folio_get_private(folio) != eb);
return 0;
}
/* Already mapped, just free prealloc */
if (folio_test_private(folio)) {
btrfs_free_subpage(prealloc);
return 0;
}
if (prealloc)
/* Has preallocated memory for subpage */
folio_attach_private(folio, prealloc);
else
/* Do new allocation to attach subpage */
ret = btrfs_attach_subpage(fs_info, folio, BTRFS_SUBPAGE_METADATA);
return ret;
}
int set_page_extent_mapped(struct page *page)
{
return set_folio_extent_mapped(page_folio(page));
}
int set_folio_extent_mapped(struct folio *folio)
{
struct btrfs_fs_info *fs_info;
ASSERT(folio->mapping);
if (folio_test_private(folio))
return 0;
fs_info = folio_to_fs_info(folio);
if (btrfs_is_subpage(fs_info, folio->mapping))
return btrfs_attach_subpage(fs_info, folio, BTRFS_SUBPAGE_DATA);
folio_attach_private(folio, (void *)EXTENT_FOLIO_PRIVATE);
return 0;
}
void clear_page_extent_mapped(struct page *page)
{
struct folio *folio = page_folio(page);
struct btrfs_fs_info *fs_info;
ASSERT(page->mapping);
if (!folio_test_private(folio))
return;
fs_info = page_to_fs_info(page);
if (btrfs_is_subpage(fs_info, page->mapping))
return btrfs_detach_subpage(fs_info, folio);
folio_detach_private(folio);
}
static struct extent_map *__get_extent_map(struct inode *inode, struct page *page,
u64 start, u64 len, struct extent_map **em_cached)
{
struct extent_map *em;
ASSERT(em_cached);
if (*em_cached) {
em = *em_cached;
if (extent_map_in_tree(em) && start >= em->start &&
start < extent_map_end(em)) {
refcount_inc(&em->refs);
return em;
}
free_extent_map(em);
*em_cached = NULL;
}
em = btrfs_get_extent(BTRFS_I(inode), page, start, len);
if (!IS_ERR(em)) {
BUG_ON(*em_cached);
refcount_inc(&em->refs);
*em_cached = em;
}
return em;
}
/*
* basic readpage implementation. Locked extent state structs are inserted
* into the tree that are removed when the IO is done (by the end_io
* handlers)
* XXX JDM: This needs looking at to ensure proper page locking
* return 0 on success, otherwise return error
*/
static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start)
{
struct inode *inode = page->mapping->host;
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
u64 start = page_offset(page);
const u64 end = start + PAGE_SIZE - 1;
u64 cur = start;
u64 extent_offset;
u64 last_byte = i_size_read(inode);
u64 block_start;
struct extent_map *em;
int ret = 0;
size_t pg_offset = 0;
size_t iosize;
size_t blocksize = fs_info->sectorsize;
struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
ret = set_page_extent_mapped(page);
if (ret < 0) {
unlock_extent(tree, start, end, NULL);
unlock_page(page);
return ret;
}
if (page->index == last_byte >> PAGE_SHIFT) {
size_t zero_offset = offset_in_page(last_byte);
if (zero_offset) {
iosize = PAGE_SIZE - zero_offset;
memzero_page(page, zero_offset, iosize);
}
}
bio_ctrl->end_io_func = end_bbio_data_read;
begin_page_read(fs_info, page);
while (cur <= end) {
enum btrfs_compression_type compress_type = BTRFS_COMPRESS_NONE;
bool force_bio_submit = false;
u64 disk_bytenr;
ASSERT(IS_ALIGNED(cur, fs_info->sectorsize));
if (cur >= last_byte) {
iosize = PAGE_SIZE - pg_offset;
memzero_page(page, pg_offset, iosize);
unlock_extent(tree, cur, cur + iosize - 1, NULL);
end_page_read(page, true, cur, iosize);
break;
}
em = __get_extent_map(inode, page, cur, end - cur + 1, em_cached);
if (IS_ERR(em)) {
unlock_extent(tree, cur, end, NULL);
end_page_read(page, false, cur, end + 1 - cur);
return PTR_ERR(em);
}
extent_offset = cur - em->start;
BUG_ON(extent_map_end(em) <= cur);
BUG_ON(end < cur);
compress_type = extent_map_compression(em);
iosize = min(extent_map_end(em) - cur, end - cur + 1);
iosize = ALIGN(iosize, blocksize);
if (compress_type != BTRFS_COMPRESS_NONE)
disk_bytenr = em->disk_bytenr;
else
disk_bytenr = extent_map_block_start(em) + extent_offset;
block_start = extent_map_block_start(em);
if (em->flags & EXTENT_FLAG_PREALLOC)
block_start = EXTENT_MAP_HOLE;
/*
* If we have a file range that points to a compressed extent
* and it's followed by a consecutive file range that points
* to the same compressed extent (possibly with a different
* offset and/or length, so it either points to the whole extent
* or only part of it), we must make sure we do not submit a
* single bio to populate the pages for the 2 ranges because
* this makes the compressed extent read zero out the pages
* belonging to the 2nd range. Imagine the following scenario:
*
* File layout
* [0 - 8K] [8K - 24K]
* | |
* | |
* points to extent X, points to extent X,
* offset 4K, length of 8K offset 0, length 16K
*
* [extent X, compressed length = 4K uncompressed length = 16K]
*
* If the bio to read the compressed extent covers both ranges,
* it will decompress extent X into the pages belonging to the
* first range and then it will stop, zeroing out the remaining
* pages that belong to the other range that points to extent X.
* So here we make sure we submit 2 bios, one for the first
* range and another one for the third range. Both will target
* the same physical extent from disk, but we can't currently
* make the compressed bio endio callback populate the pages
* for both ranges because each compressed bio is tightly
* coupled with a single extent map, and each range can have
* an extent map with a different offset value relative to the
* uncompressed data of our extent and different lengths. This
* is a corner case so we prioritize correctness over
* non-optimal behavior (submitting 2 bios for the same extent).
*/
if (compress_type != BTRFS_COMPRESS_NONE &&
prev_em_start && *prev_em_start != (u64)-1 &&
*prev_em_start != em->start)
force_bio_submit = true;
if (prev_em_start)
*prev_em_start = em->start;
free_extent_map(em);
em = NULL;
/* we've found a hole, just zero and go on */
if (block_start == EXTENT_MAP_HOLE) {
memzero_page(page, pg_offset, iosize);
unlock_extent(tree, cur, cur + iosize - 1, NULL);
end_page_read(page, true, cur, iosize);
cur = cur + iosize;
pg_offset += iosize;
continue;
}
/* the get_extent function already copied into the page */
if (block_start == EXTENT_MAP_INLINE) {
unlock_extent(tree, cur, cur + iosize - 1, NULL);
end_page_read(page, true, cur, iosize);
cur = cur + iosize;
pg_offset += iosize;
continue;
}
if (bio_ctrl->compress_type != compress_type) {
submit_one_bio(bio_ctrl);
bio_ctrl->compress_type = compress_type;
}
if (force_bio_submit)
submit_one_bio(bio_ctrl);
submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
pg_offset);
cur = cur + iosize;
pg_offset += iosize;
}
return 0;
}
int btrfs_read_folio(struct file *file, struct folio *folio)
{
struct page *page = &folio->page;
struct btrfs_inode *inode = page_to_inode(page);
u64 start = page_offset(page);
u64 end = start + PAGE_SIZE - 1;
struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ };
struct extent_map *em_cached = NULL;
int ret;
btrfs_lock_and_flush_ordered_range(inode, start, end, NULL);
ret = btrfs_do_readpage(page, &em_cached, &bio_ctrl, NULL);
free_extent_map(em_cached);
/*
* If btrfs_do_readpage() failed we will want to submit the assembled
* bio to do the cleanup.
*/
submit_one_bio(&bio_ctrl);
return ret;
}
static inline void contiguous_readpages(struct page *pages[], int nr_pages,
u64 start, u64 end,
struct extent_map **em_cached,
struct btrfs_bio_ctrl *bio_ctrl,
u64 *prev_em_start)
{
struct btrfs_inode *inode = page_to_inode(pages[0]);
int index;
ASSERT(em_cached);
btrfs_lock_and_flush_ordered_range(inode, start, end, NULL);
for (index = 0; index < nr_pages; index++) {
btrfs_do_readpage(pages[index], em_cached, bio_ctrl,
prev_em_start);
put_page(pages[index]);
}
}
/*
* helper for __extent_writepage, doing all of the delayed allocation setup.
*
* This returns 1 if btrfs_run_delalloc_range function did all the work required
* to write the page (copy into inline extent). In this case the IO has
* been started and the page is already unlocked.
*
* This returns 0 if all went well (page still locked)
* This returns < 0 if there were errors (page still locked)
*/
static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
struct page *page, struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = inode_to_fs_info(&inode->vfs_inode);
struct folio *folio = page_folio(page);
const bool is_subpage = btrfs_is_subpage(fs_info, page->mapping);
const u64 page_start = page_offset(page);
const u64 page_end = page_start + PAGE_SIZE - 1;
/*
* Save the last found delalloc end. As the delalloc end can go beyond
* page boundary, thus we cannot rely on subpage bitmap to locate the
* last delalloc end.
*/
u64 last_delalloc_end = 0;
u64 delalloc_start = page_start;
u64 delalloc_end = page_end;
u64 delalloc_to_write = 0;
int ret = 0;
/* Lock all (subpage) delalloc ranges inside the page first. */
while (delalloc_start < page_end) {
delalloc_end = page_end;
if (!find_lock_delalloc_range(&inode->vfs_inode, page,
&delalloc_start, &delalloc_end)) {
delalloc_start = delalloc_end + 1;
continue;
}
btrfs_folio_set_writer_lock(fs_info, folio, delalloc_start,
min(delalloc_end, page_end) + 1 -
delalloc_start);
last_delalloc_end = delalloc_end;
delalloc_start = delalloc_end + 1;
}
delalloc_start = page_start;
if (!last_delalloc_end)
goto out;
/* Run the delalloc ranges for the above locked ranges. */
while (delalloc_start < page_end) {
u64 found_start;
u32 found_len;
bool found;
if (!is_subpage) {
/*
* For non-subpage case, the found delalloc range must
* cover this page and there must be only one locked
* delalloc range.
*/
found_start = page_start;
found_len = last_delalloc_end + 1 - found_start;
found = true;
} else {
found = btrfs_subpage_find_writer_locked(fs_info, folio,
delalloc_start, &found_start, &found_len);
}
if (!found)
break;
/*
* The subpage range covers the last sector, the delalloc range may
* end beyond the page boundary, use the saved delalloc_end
* instead.
*/
if (found_start + found_len >= page_end)
found_len = last_delalloc_end + 1 - found_start;
if (ret >= 0) {
/* No errors hit so far, run the current delalloc range. */
ret = btrfs_run_delalloc_range(inode, page, found_start,
found_start + found_len - 1,
wbc);
} else {
/*
* We've hit an error during previous delalloc range,
* have to cleanup the remaining locked ranges.
*/
unlock_extent(&inode->io_tree, found_start,
found_start + found_len - 1, NULL);
__unlock_for_delalloc(&inode->vfs_inode, page, found_start,
found_start + found_len - 1);
}
/*
* We can hit btrfs_run_delalloc_range() with >0 return value.
*
* This happens when either the IO is already done and page
* unlocked (inline) or the IO submission and page unlock would
* be handled as async (compression).
*
* Inline is only possible for regular sectorsize for now.
*
* Compression is possible for both subpage and regular cases,
* but even for subpage compression only happens for page aligned
* range, thus the found delalloc range must go beyond current
* page.
*/
if (ret > 0)
ASSERT(!is_subpage || found_start + found_len >= page_end);
/*
* Above btrfs_run_delalloc_range() may have unlocked the page,
* thus for the last range, we cannot touch the page anymore.
*/
if (found_start + found_len >= last_delalloc_end + 1)
break;
delalloc_start = found_start + found_len;
}
if (ret < 0)
return ret;
out:
if (last_delalloc_end)
delalloc_end = last_delalloc_end;
else
delalloc_end = page_end;
/*
* delalloc_end is already one less than the total length, so
* we don't subtract one from PAGE_SIZE
*/
delalloc_to_write +=
DIV_ROUND_UP(delalloc_end + 1 - page_start, PAGE_SIZE);
/*
* If btrfs_run_dealloc_range() already started I/O and unlocked
* the pages, we just need to account for them here.
*/
if (ret == 1) {
wbc->nr_to_write -= delalloc_to_write;
return 1;
}
if (wbc->nr_to_write < delalloc_to_write) {
int thresh = 8192;
if (delalloc_to_write < thresh * 2)
thresh = delalloc_to_write;
wbc->nr_to_write = min_t(u64, delalloc_to_write,
thresh);
}
return 0;
}
/*
* Find the first byte we need to write.
*
* For subpage, one page can contain several sectors, and
* __extent_writepage_io() will just grab all extent maps in the page
* range and try to submit all non-inline/non-compressed extents.
*
* This is a big problem for subpage, we shouldn't re-submit already written
* data at all.
* This function will lookup subpage dirty bit to find which range we really
* need to submit.
*
* Return the next dirty range in [@start, @end).
* If no dirty range is found, @start will be page_offset(page) + PAGE_SIZE.
*/
static void find_next_dirty_byte(const struct btrfs_fs_info *fs_info,
struct page *page, u64 *start, u64 *end)
{
struct folio *folio = page_folio(page);
struct btrfs_subpage *subpage = folio_get_private(folio);
struct btrfs_subpage_info *spi = fs_info->subpage_info;
u64 orig_start = *start;
/* Declare as unsigned long so we can use bitmap ops */
unsigned long flags;
int range_start_bit;
int range_end_bit;
/*
* For regular sector size == page size case, since one page only
* contains one sector, we return the page offset directly.
*/
if (!btrfs_is_subpage(fs_info, page->mapping)) {
*start = page_offset(page);
*end = page_offset(page) + PAGE_SIZE;
return;
}
range_start_bit = spi->dirty_offset +
(offset_in_page(orig_start) >> fs_info->sectorsize_bits);
/* We should have the page locked, but just in case */
spin_lock_irqsave(&subpage->lock, flags);
bitmap_next_set_region(subpage->bitmaps, &range_start_bit, &range_end_bit,
spi->dirty_offset + spi->bitmap_nr_bits);
spin_unlock_irqrestore(&subpage->lock, flags);
range_start_bit -= spi->dirty_offset;
range_end_bit -= spi->dirty_offset;
*start = page_offset(page) + range_start_bit * fs_info->sectorsize;
*end = page_offset(page) + range_end_bit * fs_info->sectorsize;
}
/*
* helper for __extent_writepage. This calls the writepage start hooks,
* and does the loop to map the page into extents and bios.
*
* We return 1 if the IO is started and the page is unlocked,
* 0 if all went well (page still locked)
* < 0 if there were errors (page still locked)
*/
static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode,
struct page *page, u64 start, u32 len,
struct btrfs_bio_ctrl *bio_ctrl,
loff_t i_size,
int *nr_ret)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
u64 cur = start;
u64 end = start + len - 1;
u64 extent_offset;
u64 block_start;
struct extent_map *em;
int ret = 0;
int nr = 0;
ASSERT(start >= page_offset(page) &&
start + len <= page_offset(page) + PAGE_SIZE);
ret = btrfs_writepage_cow_fixup(page);
if (ret) {
/* Fixup worker will requeue */
redirty_page_for_writepage(bio_ctrl->wbc, page);
unlock_page(page);
return 1;
}
bio_ctrl->end_io_func = end_bbio_data_write;
while (cur <= end) {
u32 len = end - cur + 1;
u64 disk_bytenr;
u64 em_end;
u64 dirty_range_start = cur;
u64 dirty_range_end;
u32 iosize;
if (cur >= i_size) {
btrfs_mark_ordered_io_finished(inode, page, cur, len,
true);
/*
* This range is beyond i_size, thus we don't need to
* bother writing back.
* But we still need to clear the dirty subpage bit, or
* the next time the page gets dirtied, we will try to
* writeback the sectors with subpage dirty bits,
* causing writeback without ordered extent.
*/
btrfs_folio_clear_dirty(fs_info, page_folio(page), cur, len);
break;
}
find_next_dirty_byte(fs_info, page, &dirty_range_start,
&dirty_range_end);
if (cur < dirty_range_start) {
cur = dirty_range_start;
continue;
}
em = btrfs_get_extent(inode, NULL, cur, len);
if (IS_ERR(em)) {
ret = PTR_ERR_OR_ZERO(em);
goto out_error;
}
extent_offset = cur - em->start;
em_end = extent_map_end(em);
ASSERT(cur <= em_end);
ASSERT(cur < end);
ASSERT(IS_ALIGNED(em->start, fs_info->sectorsize));
ASSERT(IS_ALIGNED(em->len, fs_info->sectorsize));
block_start = extent_map_block_start(em);
disk_bytenr = extent_map_block_start(em) + extent_offset;
ASSERT(!extent_map_is_compressed(em));
ASSERT(block_start != EXTENT_MAP_HOLE);
ASSERT(block_start != EXTENT_MAP_INLINE);
/*
* Note that em_end from extent_map_end() and dirty_range_end from
* find_next_dirty_byte() are all exclusive
*/
iosize = min(min(em_end, end + 1), dirty_range_end) - cur;
free_extent_map(em);
em = NULL;
btrfs_set_range_writeback(inode, cur, cur + iosize - 1);
if (!PageWriteback(page)) {
btrfs_err(inode->root->fs_info,
"page %lu not writeback, cur %llu end %llu",
page->index, cur, end);
}
/*
* Although the PageDirty bit is cleared before entering this
* function, subpage dirty bit is not cleared.
* So clear subpage dirty bit here so next time we won't submit
* page for range already written to disk.
*/
btrfs_folio_clear_dirty(fs_info, page_folio(page), cur, iosize);
submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
cur - page_offset(page));
cur += iosize;
nr++;
}
btrfs_folio_assert_not_dirty(fs_info, page_folio(page), start, len);
*nr_ret = nr;
return 0;
out_error:
/*
* If we finish without problem, we should not only clear page dirty,
* but also empty subpage dirty bits
*/
*nr_ret = nr;
return ret;
}
/*
* the writepage semantics are similar to regular writepage. extent
* records are inserted to lock ranges in the tree, and as dirty areas
* are found, they are marked writeback. Then the lock bits are removed
* and the end_io handler clears the writeback ranges
*
* Return 0 if everything goes well.
* Return <0 for error.
*/
static int __extent_writepage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
{
struct folio *folio = page_folio(page);
struct inode *inode = page->mapping->host;
const u64 page_start = page_offset(page);
int ret;
int nr = 0;
size_t pg_offset;
loff_t i_size = i_size_read(inode);
unsigned long end_index = i_size >> PAGE_SHIFT;
trace___extent_writepage(page, inode, bio_ctrl->wbc);
WARN_ON(!PageLocked(page));
pg_offset = offset_in_page(i_size);
if (page->index > end_index ||
(page->index == end_index && !pg_offset)) {
folio_invalidate(folio, 0, folio_size(folio));
folio_unlock(folio);
return 0;
}
if (page->index == end_index)
memzero_page(page, pg_offset, PAGE_SIZE - pg_offset);
ret = set_page_extent_mapped(page);
if (ret < 0)
goto done;
ret = writepage_delalloc(BTRFS_I(inode), page, bio_ctrl->wbc);
if (ret == 1)
return 0;
if (ret)
goto done;
ret = __extent_writepage_io(BTRFS_I(inode), page, page_offset(page),
PAGE_SIZE, bio_ctrl, i_size, &nr);
if (ret == 1)
return 0;
bio_ctrl->wbc->nr_to_write--;
done:
if (nr == 0) {
/* make sure the mapping tag for page dirty gets cleared */
set_page_writeback(page);
end_page_writeback(page);
}
if (ret) {
btrfs_mark_ordered_io_finished(BTRFS_I(inode), page, page_start,
PAGE_SIZE, !ret);
mapping_set_error(page->mapping, ret);
}
btrfs_folio_end_all_writers(inode_to_fs_info(inode), folio);
ASSERT(ret <= 0);
return ret;
}
void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
{
wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
TASK_UNINTERRUPTIBLE);
}
/*
* Lock extent buffer status and pages for writeback.
*
* Return %false if the extent buffer doesn't need to be submitted (e.g. the
* extent buffer is not dirty)
* Return %true is the extent buffer is submitted to bio.
*/
static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb,
struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
bool ret = false;
btrfs_tree_lock(eb);
while (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
btrfs_tree_unlock(eb);
if (wbc->sync_mode != WB_SYNC_ALL)
return false;
wait_on_extent_buffer_writeback(eb);
btrfs_tree_lock(eb);
}
/*
* We need to do this to prevent races in people who check if the eb is
* under IO since we can end up having no IO bits set for a short period
* of time.
*/
spin_lock(&eb->refs_lock);
if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
spin_unlock(&eb->refs_lock);
btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
-eb->len,
fs_info->dirty_metadata_batch);
ret = true;
} else {
spin_unlock(&eb->refs_lock);
}
btrfs_tree_unlock(eb);
return ret;
}
static void set_btree_ioerr(struct extent_buffer *eb)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
/*
* A read may stumble upon this buffer later, make sure that it gets an
* error and knows there was an error.
*/
clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
/*
* We need to set the mapping with the io error as well because a write
* error will flip the file system readonly, and then syncfs() will
* return a 0 because we are readonly if we don't modify the err seq for
* the superblock.
*/
mapping_set_error(eb->fs_info->btree_inode->i_mapping, -EIO);
/*
* If writeback for a btree extent that doesn't belong to a log tree
* failed, increment the counter transaction->eb_write_errors.
* We do this because while the transaction is running and before it's
* committing (when we call filemap_fdata[write|wait]_range against
* the btree inode), we might have
* btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
* returns an error or an error happens during writeback, when we're
* committing the transaction we wouldn't know about it, since the pages
* can be no longer dirty nor marked anymore for writeback (if a
* subsequent modification to the extent buffer didn't happen before the
* transaction commit), which makes filemap_fdata[write|wait]_range not
* able to find the pages which contain errors at transaction
* commit time. So if this happens we must abort the transaction,
* otherwise we commit a super block with btree roots that point to
* btree nodes/leafs whose content on disk is invalid - either garbage
* or the content of some node/leaf from a past generation that got
* cowed or deleted and is no longer valid.
*
* Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
* not be enough - we need to distinguish between log tree extents vs
* non-log tree extents, and the next filemap_fdatawait_range() call
* will catch and clear such errors in the mapping - and that call might
* be from a log sync and not from a transaction commit. Also, checking
* for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
* not done and would not be reliable - the eb might have been released
* from memory and reading it back again means that flag would not be
* set (since it's a runtime flag, not persisted on disk).
*
* Using the flags below in the btree inode also makes us achieve the
* goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
* writeback for all dirty pages and before filemap_fdatawait_range()
* is called, the writeback for all dirty pages had already finished
* with errors - because we were not using AS_EIO/AS_ENOSPC,
* filemap_fdatawait_range() would return success, as it could not know
* that writeback errors happened (the pages were no longer tagged for
* writeback).
*/
switch (eb->log_index) {
case -1:
set_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags);
break;
case 0:
set_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
break;
case 1:
set_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
break;
default:
BUG(); /* unexpected, logic error */
}
}
/*
* The endio specific version which won't touch any unsafe spinlock in endio
* context.
*/
static struct extent_buffer *find_extent_buffer_nolock(
const struct btrfs_fs_info *fs_info, u64 start)
{
struct extent_buffer *eb;
rcu_read_lock();
eb = radix_tree_lookup(&fs_info->buffer_radix,
start >> fs_info->sectorsize_bits);
if (eb && atomic_inc_not_zero(&eb->refs)) {
rcu_read_unlock();
return eb;
}
rcu_read_unlock();
return NULL;
}
static void end_bbio_meta_write(struct btrfs_bio *bbio)
{
struct extent_buffer *eb = bbio->private;
struct btrfs_fs_info *fs_info = eb->fs_info;
bool uptodate = !bbio->bio.bi_status;
struct folio_iter fi;
u32 bio_offset = 0;
if (!uptodate)
set_btree_ioerr(eb);
bio_for_each_folio_all(fi, &bbio->bio) {
u64 start = eb->start + bio_offset;
struct folio *folio = fi.folio;
u32 len = fi.length;
btrfs_folio_clear_writeback(fs_info, folio, start, len);
bio_offset += len;
}
clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
smp_mb__after_atomic();
wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
bio_put(&bbio->bio);
}
static void prepare_eb_write(struct extent_buffer *eb)
{
u32 nritems;
unsigned long start;
unsigned long end;
clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
/* Set btree blocks beyond nritems with 0 to avoid stale content */
nritems = btrfs_header_nritems(eb);
if (btrfs_header_level(eb) > 0) {
end = btrfs_node_key_ptr_offset(eb, nritems);
memzero_extent_buffer(eb, end, eb->len - end);
} else {
/*
* Leaf:
* header 0 1 2 .. N ... data_N .. data_2 data_1 data_0
*/
start = btrfs_item_nr_offset(eb, nritems);
end = btrfs_item_nr_offset(eb, 0);
if (nritems == 0)
end += BTRFS_LEAF_DATA_SIZE(eb->fs_info);
else
end += btrfs_item_offset(eb, nritems - 1);
memzero_extent_buffer(eb, start, end - start);
}
}
static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
struct btrfs_bio *bbio;
prepare_eb_write(eb);
bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),
eb->fs_info, end_bbio_meta_write, eb);
bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev);
wbc_init_bio(wbc, &bbio->bio);
bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
bbio->file_offset = eb->start;
if (fs_info->nodesize < PAGE_SIZE) {
struct folio *folio = eb->folios[0];
bool ret;
folio_lock(folio);
btrfs_subpage_set_writeback(fs_info, folio, eb->start, eb->len);
if (btrfs_subpage_clear_and_test_dirty(fs_info, folio, eb->start,
eb->len)) {
folio_clear_dirty_for_io(folio);
wbc->nr_to_write--;
}
ret = bio_add_folio(&bbio->bio, folio, eb->len,
eb->start - folio_pos(folio));
ASSERT(ret);
wbc_account_cgroup_owner(wbc, folio_page(folio, 0), eb->len);
folio_unlock(folio);
} else {
int num_folios = num_extent_folios(eb);
for (int i = 0; i < num_folios; i++) {
struct folio *folio = eb->folios[i];
bool ret;
folio_lock(folio);
folio_clear_dirty_for_io(folio);
folio_start_writeback(folio);
ret = bio_add_folio(&bbio->bio, folio, eb->folio_size, 0);
ASSERT(ret);
wbc_account_cgroup_owner(wbc, folio_page(folio, 0),
eb->folio_size);
wbc->nr_to_write -= folio_nr_pages(folio);
folio_unlock(folio);
}
}
btrfs_submit_bio(bbio, 0);
}
/*
* Submit one subpage btree page.
*
* The main difference to submit_eb_page() is:
* - Page locking
* For subpage, we don't rely on page locking at all.
*
* - Flush write bio
* We only flush bio if we may be unable to fit current extent buffers into
* current bio.
*
* Return >=0 for the number of submitted extent buffers.
* Return <0 for fatal error.
*/
static int submit_eb_subpage(struct page *page, struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = page_to_fs_info(page);
struct folio *folio = page_folio(page);
int submitted = 0;
u64 page_start = page_offset(page);
int bit_start = 0;
int sectors_per_node = fs_info->nodesize >> fs_info->sectorsize_bits;
/* Lock and write each dirty extent buffers in the range */
while (bit_start < fs_info->subpage_info->bitmap_nr_bits) {
struct btrfs_subpage *subpage = folio_get_private(folio);
struct extent_buffer *eb;
unsigned long flags;
u64 start;
/*
* Take private lock to ensure the subpage won't be detached
* in the meantime.
*/
spin_lock(&page->mapping->i_private_lock);
if (!folio_test_private(folio)) {
spin_unlock(&page->mapping->i_private_lock);
break;
}
spin_lock_irqsave(&subpage->lock, flags);
if (!test_bit(bit_start + fs_info->subpage_info->dirty_offset,
subpage->bitmaps)) {
spin_unlock_irqrestore(&subpage->lock, flags);
spin_unlock(&page->mapping->i_private_lock);
bit_start++;
continue;
}
start = page_start + bit_start * fs_info->sectorsize;
bit_start += sectors_per_node;
/*
* Here we just want to grab the eb without touching extra
* spin locks, so call find_extent_buffer_nolock().
*/
eb = find_extent_buffer_nolock(fs_info, start);
spin_unlock_irqrestore(&subpage->lock, flags);
spin_unlock(&page->mapping->i_private_lock);
/*
* The eb has already reached 0 refs thus find_extent_buffer()
* doesn't return it. We don't need to write back such eb
* anyway.
*/
if (!eb)
continue;
if (lock_extent_buffer_for_io(eb, wbc)) {
write_one_eb(eb, wbc);
submitted++;
}
free_extent_buffer(eb);
}
return submitted;
}
/*
* Submit all page(s) of one extent buffer.
*
* @page: the page of one extent buffer
* @eb_context: to determine if we need to submit this page, if current page
* belongs to this eb, we don't need to submit
*
* The caller should pass each page in their bytenr order, and here we use
* @eb_context to determine if we have submitted pages of one extent buffer.
*
* If we have, we just skip until we hit a new page that doesn't belong to
* current @eb_context.
*
* If not, we submit all the page(s) of the extent buffer.
*
* Return >0 if we have submitted the extent buffer successfully.
* Return 0 if we don't need to submit the page, as it's already submitted by
* previous call.
* Return <0 for fatal error.
*/
static int submit_eb_page(struct page *page, struct btrfs_eb_write_context *ctx)
{
struct writeback_control *wbc = ctx->wbc;
struct address_space *mapping = page->mapping;
struct folio *folio = page_folio(page);
struct extent_buffer *eb;
int ret;
if (!folio_test_private(folio))
return 0;
if (page_to_fs_info(page)->nodesize < PAGE_SIZE)
return submit_eb_subpage(page, wbc);
spin_lock(&mapping->i_private_lock);
if (!folio_test_private(folio)) {
spin_unlock(&mapping->i_private_lock);
return 0;
}
eb = folio_get_private(folio);
/*
* Shouldn't happen and normally this would be a BUG_ON but no point
* crashing the machine for something we can survive anyway.
*/
if (WARN_ON(!eb)) {
spin_unlock(&mapping->i_private_lock);
return 0;
}
if (eb == ctx->eb) {
spin_unlock(&mapping->i_private_lock);
return 0;
}
ret = atomic_inc_not_zero(&eb->refs);
spin_unlock(&mapping->i_private_lock);
if (!ret)
return 0;
ctx->eb = eb;
ret = btrfs_check_meta_write_pointer(eb->fs_info, ctx);
if (ret) {
if (ret == -EBUSY)
ret = 0;
free_extent_buffer(eb);
return ret;
}
if (!lock_extent_buffer_for_io(eb, wbc)) {
free_extent_buffer(eb);
return 0;
}
/* Implies write in zoned mode. */
if (ctx->zoned_bg) {
/* Mark the last eb in the block group. */
btrfs_schedule_zone_finish_bg(ctx->zoned_bg, eb);
ctx->zoned_bg->meta_write_pointer += eb->len;
}
write_one_eb(eb, wbc);
free_extent_buffer(eb);
return 1;
}
int btree_write_cache_pages(struct address_space *mapping,
struct writeback_control *wbc)
{
struct btrfs_eb_write_context ctx = { .wbc = wbc };
struct btrfs_fs_info *fs_info = inode_to_fs_info(mapping->host);
int ret = 0;
int done = 0;
int nr_to_write_done = 0;
struct folio_batch fbatch;
unsigned int nr_folios;
pgoff_t index;
pgoff_t end; /* Inclusive */
int scanned = 0;
xa_mark_t tag;
folio_batch_init(&fbatch);
if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */
end = -1;
/*
* Start from the beginning does not need to cycle over the
* range, mark it as scanned.
*/
scanned = (index == 0);
} else {
index = wbc->range_start >> PAGE_SHIFT;
end = wbc->range_end >> PAGE_SHIFT;
scanned = 1;
}
if (wbc->sync_mode == WB_SYNC_ALL)
tag = PAGECACHE_TAG_TOWRITE;
else
tag = PAGECACHE_TAG_DIRTY;
btrfs_zoned_meta_io_lock(fs_info);
retry:
if (wbc->sync_mode == WB_SYNC_ALL)
tag_pages_for_writeback(mapping, index, end);
while (!done && !nr_to_write_done && (index <= end) &&
(nr_folios = filemap_get_folios_tag(mapping, &index, end,
tag, &fbatch))) {
unsigned i;
for (i = 0; i < nr_folios; i++) {
struct folio *folio = fbatch.folios[i];
ret = submit_eb_page(&folio->page, &ctx);
if (ret == 0)
continue;
if (ret < 0) {
done = 1;
break;
}
/*
* the filesystem may choose to bump up nr_to_write.
* We have to make sure to honor the new nr_to_write
* at any time
*/
nr_to_write_done = wbc->nr_to_write <= 0;
}
folio_batch_release(&fbatch);
cond_resched();
}
if (!scanned && !done) {
/*
* We hit the last page and there is more work to be done: wrap
* back to the start of the file
*/
scanned = 1;
index = 0;
goto retry;
}
/*
* If something went wrong, don't allow any metadata write bio to be
* submitted.
*
* This would prevent use-after-free if we had dirty pages not
* cleaned up, which can still happen by fuzzed images.
*
* - Bad extent tree
* Allowing existing tree block to be allocated for other trees.
*
* - Log tree operations
* Exiting tree blocks get allocated to log tree, bumps its
* generation, then get cleaned in tree re-balance.
* Such tree block will not be written back, since it's clean,
* thus no WRITTEN flag set.
* And after log writes back, this tree block is not traced by
* any dirty extent_io_tree.
*
* - Offending tree block gets re-dirtied from its original owner
* Since it has bumped generation, no WRITTEN flag, it can be
* reused without COWing. This tree block will not be traced
* by btrfs_transaction::dirty_pages.
*
* Now such dirty tree block will not be cleaned by any dirty
* extent io tree. Thus we don't want to submit such wild eb
* if the fs already has error.
*
* We can get ret > 0 from submit_extent_page() indicating how many ebs
* were submitted. Reset it to 0 to avoid false alerts for the caller.
*/
if (ret > 0)
ret = 0;
if (!ret && BTRFS_FS_ERROR(fs_info))
ret = -EROFS;
if (ctx.zoned_bg)
btrfs_put_block_group(ctx.zoned_bg);
btrfs_zoned_meta_io_unlock(fs_info);
return ret;
}
/*
* Walk the list of dirty pages of the given address space and write all of them.
*
* @mapping: address space structure to write
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
* @bio_ctrl: holds context for the write, namely the bio
*
* If a page is already under I/O, write_cache_pages() 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.
*/
static int extent_write_cache_pages(struct address_space *mapping,
struct btrfs_bio_ctrl *bio_ctrl)
{
struct writeback_control *wbc = bio_ctrl->wbc;
struct inode *inode = mapping->host;
int ret = 0;
int done = 0;
int nr_to_write_done = 0;
struct folio_batch fbatch;
unsigned int nr_folios;
pgoff_t index;
pgoff_t end; /* Inclusive */
pgoff_t done_index;
int range_whole = 0;
int scanned = 0;
xa_mark_t tag;
/*
* We have to hold onto the inode so that ordered extents can do their
* work when the IO finishes. The alternative to this is failing to add
* an ordered extent if the igrab() fails there and that is a huge pain
* to deal with, so instead just hold onto the inode throughout the
* writepages operation. If it fails here we are freeing up the inode
* anyway and we'd rather not waste our time writing out stuff that is
* going to be truncated anyway.
*/
if (!igrab(inode))
return 0;
folio_batch_init(&fbatch);
if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */
end = -1;
/*
* Start from the beginning does not need to cycle over the
* range, mark it as scanned.
*/
scanned = (index == 0);
} else {
index = wbc->range_start >> PAGE_SHIFT;
end = wbc->range_end >> PAGE_SHIFT;
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
range_whole = 1;
scanned = 1;
}
/*
* We do the tagged writepage as long as the snapshot flush bit is set
* and we are the first one who do the filemap_flush() on this inode.
*
* The nr_to_write == LONG_MAX is needed to make sure other flushers do
* not race in and drop the bit.
*/
if (range_whole && wbc->nr_to_write == LONG_MAX &&
test_and_clear_bit(BTRFS_INODE_SNAPSHOT_FLUSH,
&BTRFS_I(inode)->runtime_flags))
wbc->tagged_writepages = 1;
if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
tag = PAGECACHE_TAG_TOWRITE;
else
tag = PAGECACHE_TAG_DIRTY;
retry:
if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
tag_pages_for_writeback(mapping, index, end);
done_index = index;
while (!done && !nr_to_write_done && (index <= end) &&
(nr_folios = filemap_get_folios_tag(mapping, &index,
end, tag, &fbatch))) {
unsigned i;
for (i = 0; i < nr_folios; i++) {
struct folio *folio = fbatch.folios[i];
done_index = folio_next_index(folio);
/*
* At this point we hold neither the i_pages lock nor
* the page lock: the page may be truncated or
* invalidated (changing page->mapping to NULL),
* or even swizzled back from swapper_space to
* tmpfs file mapping
*/
if (!folio_trylock(folio)) {
submit_write_bio(bio_ctrl, 0);
folio_lock(folio);
}
if (unlikely(folio->mapping != mapping)) {
folio_unlock(folio);
continue;
}
if (!folio_test_dirty(folio)) {
/* Someone wrote it for us. */
folio_unlock(folio);
continue;
}
if (wbc->sync_mode != WB_SYNC_NONE) {
if (folio_test_writeback(folio))
submit_write_bio(bio_ctrl, 0);
folio_wait_writeback(folio);
}
if (folio_test_writeback(folio) ||
!folio_clear_dirty_for_io(folio)) {
folio_unlock(folio);
continue;
}
ret = __extent_writepage(&folio->page, bio_ctrl);
if (ret < 0) {
done = 1;
break;
}
/*
* The filesystem may choose to bump up nr_to_write.
* We have to make sure to honor the new nr_to_write
* at any time.
*/
nr_to_write_done = (wbc->sync_mode == WB_SYNC_NONE &&
wbc->nr_to_write <= 0);
}
folio_batch_release(&fbatch);
cond_resched();
}
if (!scanned && !done) {
/*
* We hit the last page and there is more work to be done: wrap
* back to the start of the file
*/
scanned = 1;
index = 0;
/*
* If we're looping we could run into a page that is locked by a
* writer and that writer could be waiting on writeback for a
* page in our current bio, and thus deadlock, so flush the
* write bio here.
*/
submit_write_bio(bio_ctrl, 0);
goto retry;
}
if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole))
mapping->writeback_index = done_index;
btrfs_add_delayed_iput(BTRFS_I(inode));
return ret;
}
/*
* Submit the pages in the range to bio for call sites which delalloc range has
* already been ran (aka, ordered extent inserted) and all pages are still
* locked.
*/
void extent_write_locked_range(struct inode *inode, const struct page *locked_page,
u64 start, u64 end, struct writeback_control *wbc,
bool pages_dirty)
{
bool found_error = false;
int ret = 0;
struct address_space *mapping = inode->i_mapping;
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
const u32 sectorsize = fs_info->sectorsize;
loff_t i_size = i_size_read(inode);
u64 cur = start;
struct btrfs_bio_ctrl bio_ctrl = {
.wbc = wbc,
.opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
};
if (wbc->no_cgroup_owner)
bio_ctrl.opf |= REQ_BTRFS_CGROUP_PUNT;
ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(end + 1, sectorsize));
while (cur <= end) {
u64 cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end);
u32 cur_len = cur_end + 1 - cur;
struct page *page;
int nr = 0;
page = find_get_page(mapping, cur >> PAGE_SHIFT);
ASSERT(PageLocked(page));
if (pages_dirty && page != locked_page)
ASSERT(PageDirty(page));
ret = __extent_writepage_io(BTRFS_I(inode), page, cur, cur_len,
&bio_ctrl, i_size, &nr);
if (ret == 1)
goto next_page;
/* Make sure the mapping tag for page dirty gets cleared. */
if (nr == 0) {
struct folio *folio;
folio = page_folio(page);
btrfs_folio_set_writeback(fs_info, folio, cur, cur_len);
btrfs_folio_clear_writeback(fs_info, folio, cur, cur_len);
}
if (ret) {
btrfs_mark_ordered_io_finished(BTRFS_I(inode), page,
cur, cur_len, !ret);
mapping_set_error(page->mapping, ret);
}
btrfs_folio_unlock_writer(fs_info, page_folio(page), cur, cur_len);
if (ret < 0)
found_error = true;
next_page:
put_page(page);
cur = cur_end + 1;
}
submit_write_bio(&bio_ctrl, found_error ? ret : 0);
}
int btrfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
struct inode *inode = mapping->host;
int ret = 0;
struct btrfs_bio_ctrl bio_ctrl = {
.wbc = wbc,
.opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
};
/*
* Allow only a single thread to do the reloc work in zoned mode to
* protect the write pointer updates.
*/
btrfs_zoned_data_reloc_lock(BTRFS_I(inode));
ret = extent_write_cache_pages(mapping, &bio_ctrl);
submit_write_bio(&bio_ctrl, ret);
btrfs_zoned_data_reloc_unlock(BTRFS_I(inode));
return ret;
}
void btrfs_readahead(struct readahead_control *rac)
{
struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ | REQ_RAHEAD };
struct page *pagepool[16];
struct extent_map *em_cached = NULL;
u64 prev_em_start = (u64)-1;
int nr;
while ((nr = readahead_page_batch(rac, pagepool))) {
u64 contig_start = readahead_pos(rac);
u64 contig_end = contig_start + readahead_batch_length(rac) - 1;
contiguous_readpages(pagepool, nr, contig_start, contig_end,
&em_cached, &bio_ctrl, &prev_em_start);
}
if (em_cached)
free_extent_map(em_cached);
submit_one_bio(&bio_ctrl);
}
/*
* basic invalidate_folio code, this waits on any locked or writeback
* ranges corresponding to the folio, and then deletes any extent state
* records from the tree
*/
int extent_invalidate_folio(struct extent_io_tree *tree,
struct folio *folio, size_t offset)
{
struct extent_state *cached_state = NULL;
u64 start = folio_pos(folio);
u64 end = start + folio_size(folio) - 1;
size_t blocksize = folio_to_fs_info(folio)->sectorsize;
/* This function is only called for the btree inode */
ASSERT(tree->owner == IO_TREE_BTREE_INODE_IO);
start += ALIGN(offset, blocksize);
if (start > end)
return 0;
lock_extent(tree, start, end, &cached_state);
folio_wait_writeback(folio);
/*
* Currently for btree io tree, only EXTENT_LOCKED is utilized,
* so here we only need to unlock the extent range to free any
* existing extent state.
*/
unlock_extent(tree, start, end, &cached_state);
return 0;
}
/*
* a helper for release_folio, this tests for areas of the page that
* are locked or under IO and drops the related state bits if it is safe
* to drop the page.
*/
static bool try_release_extent_state(struct extent_io_tree *tree,
struct page *page, gfp_t mask)
{
u64 start = page_offset(page);
u64 end = start + PAGE_SIZE - 1;
bool ret;
if (test_range_bit_exists(tree, start, end, EXTENT_LOCKED)) {
ret = false;
} else {
u32 clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM |
EXTENT_DELALLOC_NEW | EXTENT_CTLBITS |
EXTENT_QGROUP_RESERVED);
int ret2;
/*
* At this point we can safely clear everything except the
* locked bit, the nodatasum bit and the delalloc new bit.
* The delalloc new bit will be cleared by ordered extent
* completion.
*/
ret2 = __clear_extent_bit(tree, start, end, clear_bits, NULL, NULL);
/* if clear_extent_bit failed for enomem reasons,
* we can't allow the release to continue.
*/
if (ret2 < 0)
ret = false;
else
ret = true;
}
return ret;
}
/*
* a helper for release_folio. As long as there are no locked extents
* in the range corresponding to the page, both state records and extent
* map records are removed
*/
bool try_release_extent_mapping(struct page *page, gfp_t mask)
{
u64 start = page_offset(page);
u64 end = start + PAGE_SIZE - 1;
struct btrfs_inode *inode = page_to_inode(page);
struct extent_io_tree *io_tree = &inode->io_tree;
while (start <= end) {
const u64 cur_gen = btrfs_get_fs_generation(inode->root->fs_info);
const u64 len = end - start + 1;
struct extent_map_tree *extent_tree = &inode->extent_tree;
struct extent_map *em;
write_lock(&extent_tree->lock);
em = lookup_extent_mapping(extent_tree, start, len);
if (!em) {
write_unlock(&extent_tree->lock);
break;
}
if ((em->flags & EXTENT_FLAG_PINNED) || em->start != start) {
write_unlock(&extent_tree->lock);
free_extent_map(em);
break;
}
if (test_range_bit_exists(io_tree, em->start,
extent_map_end(em) - 1, EXTENT_LOCKED))
goto next;
/*
* If it's not in the list of modified extents, used by a fast
* fsync, we can remove it. If it's being logged we can safely
* remove it since fsync took an extra reference on the em.
*/
if (list_empty(&em->list) || (em->flags & EXTENT_FLAG_LOGGING))
goto remove_em;
/*
* If it's in the list of modified extents, remove it only if
* its generation is older then the current one, in which case
* we don't need it for a fast fsync. Otherwise don't remove it,
* we could be racing with an ongoing fast fsync that could miss
* the new extent.
*/
if (em->generation >= cur_gen)
goto next;
remove_em:
/*
* We only remove extent maps that are not in the list of
* modified extents or that are in the list but with a
* generation lower then the current generation, so there is no
* need to set the full fsync flag on the inode (it hurts the
* fsync performance for workloads with a data size that exceeds
* or is close to the system's memory).
*/
remove_extent_mapping(inode, em);
/* Once for the inode's extent map tree. */
free_extent_map(em);
next:
start = extent_map_end(em);
write_unlock(&extent_tree->lock);
/* Once for us, for the lookup_extent_mapping() reference. */
free_extent_map(em);
if (need_resched()) {
/*
* If we need to resched but we can't block just exit
* and leave any remaining extent maps.
*/
if (!gfpflags_allow_blocking(mask))
break;
cond_resched();
}
}
return try_release_extent_state(io_tree, page, mask);
}
static void __free_extent_buffer(struct extent_buffer *eb)
{
kmem_cache_free(extent_buffer_cache, eb);
}
static int extent_buffer_under_io(const struct extent_buffer *eb)
{
return (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
}
static bool folio_range_has_eb(struct btrfs_fs_info *fs_info, struct folio *folio)
{
struct btrfs_subpage *subpage;
lockdep_assert_held(&folio->mapping->i_private_lock);
if (folio_test_private(folio)) {
subpage = folio_get_private(folio);
if (atomic_read(&subpage->eb_refs))
return true;
/*
* Even there is no eb refs here, we may still have
* end_page_read() call relying on page::private.
*/
if (atomic_read(&subpage->readers))
return true;
}
return false;
}
static void detach_extent_buffer_folio(const struct extent_buffer *eb, struct folio *folio)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
const bool mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
/*
* For mapped eb, we're going to change the folio private, which should
* be done under the i_private_lock.
*/
if (mapped)
spin_lock(&folio->mapping->i_private_lock);
if (!folio_test_private(folio)) {
if (mapped)
spin_unlock(&folio->mapping->i_private_lock);
return;
}
if (fs_info->nodesize >= PAGE_SIZE) {
/*
* We do this since we'll remove the pages after we've
* removed the eb from the radix tree, so we could race
* and have this page now attached to the new eb. So
* only clear folio if it's still connected to
* this eb.
*/
if (folio_test_private(folio) && folio_get_private(folio) == eb) {
BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
BUG_ON(folio_test_dirty(folio));
BUG_ON(folio_test_writeback(folio));
/* We need to make sure we haven't be attached to a new eb. */
folio_detach_private(folio);
}
if (mapped)
spin_unlock(&folio->mapping->i_private_lock);
return;
}
/*
* For subpage, we can have dummy eb with folio private attached. In
* this case, we can directly detach the private as such folio is only
* attached to one dummy eb, no sharing.
*/
if (!mapped) {
btrfs_detach_subpage(fs_info, folio);
return;
}
btrfs_folio_dec_eb_refs(fs_info, folio);
/*
* We can only detach the folio private if there are no other ebs in the
* page range and no unfinished IO.
*/
if (!folio_range_has_eb(fs_info, folio))
btrfs_detach_subpage(fs_info, folio);
spin_unlock(&folio->mapping->i_private_lock);
}
/* Release all pages attached to the extent buffer */
static void btrfs_release_extent_buffer_pages(const struct extent_buffer *eb)
{
ASSERT(!extent_buffer_under_io(eb));
for (int i = 0; i < INLINE_EXTENT_BUFFER_PAGES; i++) {
struct folio *folio = eb->folios[i];
if (!folio)
continue;
detach_extent_buffer_folio(eb, folio);
/* One for when we allocated the folio. */
folio_put(folio);
}
}
/*
* Helper for releasing the extent buffer.
*/
static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
{
btrfs_release_extent_buffer_pages(eb);
btrfs_leak_debug_del_eb(eb);
__free_extent_buffer(eb);
}
static struct extent_buffer *
__alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
unsigned long len)
{
struct extent_buffer *eb = NULL;
eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
eb->start = start;
eb->len = len;
eb->fs_info = fs_info;
init_rwsem(&eb->lock);
btrfs_leak_debug_add_eb(eb);
spin_lock_init(&eb->refs_lock);
atomic_set(&eb->refs, 1);
ASSERT(len <= BTRFS_MAX_METADATA_BLOCKSIZE);
return eb;
}
struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src)
{
struct extent_buffer *new;
int num_folios = num_extent_folios(src);
int ret;
new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
if (new == NULL)
return NULL;
/*
* Set UNMAPPED before calling btrfs_release_extent_buffer(), as
* btrfs_release_extent_buffer() have different behavior for
* UNMAPPED subpage extent buffer.
*/
set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);
ret = alloc_eb_folio_array(new, false);
if (ret) {
btrfs_release_extent_buffer(new);
return NULL;
}
for (int i = 0; i < num_folios; i++) {
struct folio *folio = new->folios[i];
ret = attach_extent_buffer_folio(new, folio, NULL);
if (ret < 0) {
btrfs_release_extent_buffer(new);
return NULL;
}
WARN_ON(folio_test_dirty(folio));
}
copy_extent_buffer_full(new, src);
set_extent_buffer_uptodate(new);
return new;
}
struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start, unsigned long len)
{
struct extent_buffer *eb;
int num_folios = 0;
int ret;
eb = __alloc_extent_buffer(fs_info, start, len);
if (!eb)
return NULL;
ret = alloc_eb_folio_array(eb, false);
if (ret)
goto err;
num_folios = num_extent_folios(eb);
for (int i = 0; i < num_folios; i++) {
ret = attach_extent_buffer_folio(eb, eb->folios[i], NULL);
if (ret < 0)
goto err;
}
set_extent_buffer_uptodate(eb);
btrfs_set_header_nritems(eb, 0);
set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
return eb;
err:
for (int i = 0; i < num_folios; i++) {
if (eb->folios[i]) {
detach_extent_buffer_folio(eb, eb->folios[i]);
folio_put(eb->folios[i]);
}
}
__free_extent_buffer(eb);
return NULL;
}
struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start)
{
return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize);
}
static void check_buffer_tree_ref(struct extent_buffer *eb)
{
int refs;
/*
* The TREE_REF bit is first set when the extent_buffer is added
* to the radix tree. It is also reset, if unset, when a new reference
* is created by find_extent_buffer.
*
* It is only cleared in two cases: freeing the last non-tree
* reference to the extent_buffer when its STALE bit is set or
* calling release_folio when the tree reference is the only reference.
*
* In both cases, care is taken to ensure that the extent_buffer's
* pages are not under io. However, release_folio can be concurrently
* called with creating new references, which is prone to race
* conditions between the calls to check_buffer_tree_ref in those
* codepaths and clearing TREE_REF in try_release_extent_buffer.
*
* The actual lifetime of the extent_buffer in the radix tree is
* adequately protected by the refcount, but the TREE_REF bit and
* its corresponding reference are not. To protect against this
* class of races, we call check_buffer_tree_ref from the codepaths
* which trigger io. Note that once io is initiated, TREE_REF can no
* longer be cleared, so that is the moment at which any such race is
* best fixed.
*/
refs = atomic_read(&eb->refs);
if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
return;
spin_lock(&eb->refs_lock);
if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
atomic_inc(&eb->refs);
spin_unlock(&eb->refs_lock);
}
static void mark_extent_buffer_accessed(struct extent_buffer *eb)
{
int num_folios= num_extent_folios(eb);
check_buffer_tree_ref(eb);
for (int i = 0; i < num_folios; i++)
folio_mark_accessed(eb->folios[i]);
}
struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start)
{
struct extent_buffer *eb;
eb = find_extent_buffer_nolock(fs_info, start);
if (!eb)
return NULL;
/*
* Lock our eb's refs_lock to avoid races with free_extent_buffer().
* When we get our eb it might be flagged with EXTENT_BUFFER_STALE and
* another task running free_extent_buffer() might have seen that flag
* set, eb->refs == 2, that the buffer isn't under IO (dirty and
* writeback flags not set) and it's still in the tree (flag
* EXTENT_BUFFER_TREE_REF set), therefore being in the process of
* decrementing the extent buffer's reference count twice. So here we
* could race and increment the eb's reference count, clear its stale
* flag, mark it as dirty and drop our reference before the other task
* finishes executing free_extent_buffer, which would later result in
* an attempt to free an extent buffer that is dirty.
*/
if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
spin_lock(&eb->refs_lock);
spin_unlock(&eb->refs_lock);
}
mark_extent_buffer_accessed(eb);
return eb;
}
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start)
{
struct extent_buffer *eb, *exists = NULL;
int ret;
eb = find_extent_buffer(fs_info, start);
if (eb)
return eb;
eb = alloc_dummy_extent_buffer(fs_info, start);
if (!eb)
return ERR_PTR(-ENOMEM);
eb->fs_info = fs_info;
again:
ret = radix_tree_preload(GFP_NOFS);
if (ret) {
exists = ERR_PTR(ret);
goto free_eb;
}
spin_lock(&fs_info->buffer_lock);
ret = radix_tree_insert(&fs_info->buffer_radix,
start >> fs_info->sectorsize_bits, eb);
spin_unlock(&fs_info->buffer_lock);
radix_tree_preload_end();
if (ret == -EEXIST) {
exists = find_extent_buffer(fs_info, start);
if (exists)
goto free_eb;
else
goto again;
}
check_buffer_tree_ref(eb);
set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
return eb;
free_eb:
btrfs_release_extent_buffer(eb);
return exists;
}
#endif
static struct extent_buffer *grab_extent_buffer(
struct btrfs_fs_info *fs_info, struct page *page)
{
struct folio *folio = page_folio(page);
struct extent_buffer *exists;
lockdep_assert_held(&page->mapping->i_private_lock);
/*
* For subpage case, we completely rely on radix tree to ensure we
* don't try to insert two ebs for the same bytenr. So here we always
* return NULL and just continue.
*/
if (fs_info->nodesize < PAGE_SIZE)
return NULL;
/* Page not yet attached to an extent buffer */
if (!folio_test_private(folio))
return NULL;
/*
* We could have already allocated an eb for this page and attached one
* so lets see if we can get a ref on the existing eb, and if we can we
* know it's good and we can just return that one, else we know we can
* just overwrite folio private.
*/
exists = folio_get_private(folio);
if (atomic_inc_not_zero(&exists->refs))
return exists;
WARN_ON(PageDirty(page));
folio_detach_private(folio);
return NULL;
}
static int check_eb_alignment(struct btrfs_fs_info *fs_info, u64 start)
{
if (!IS_ALIGNED(start, fs_info->sectorsize)) {
btrfs_err(fs_info, "bad tree block start %llu", start);
return -EINVAL;
}
if (fs_info->nodesize < PAGE_SIZE &&
offset_in_page(start) + fs_info->nodesize > PAGE_SIZE) {
btrfs_err(fs_info,
"tree block crosses page boundary, start %llu nodesize %u",
start, fs_info->nodesize);
return -EINVAL;
}
if (fs_info->nodesize >= PAGE_SIZE &&
!PAGE_ALIGNED(start)) {
btrfs_err(fs_info,
"tree block is not page aligned, start %llu nodesize %u",
start, fs_info->nodesize);
return -EINVAL;
}
if (!IS_ALIGNED(start, fs_info->nodesize) &&
!test_and_set_bit(BTRFS_FS_UNALIGNED_TREE_BLOCK, &fs_info->flags)) {
btrfs_warn(fs_info,
"tree block not nodesize aligned, start %llu nodesize %u, can be resolved by a full metadata balance",
start, fs_info->nodesize);
}
return 0;
}
/*
* Return 0 if eb->folios[i] is attached to btree inode successfully.
* Return >0 if there is already another extent buffer for the range,
* and @found_eb_ret would be updated.
* Return -EAGAIN if the filemap has an existing folio but with different size
* than @eb.
* The caller needs to free the existing folios and retry using the same order.
*/
static int attach_eb_folio_to_filemap(struct extent_buffer *eb, int i,
struct btrfs_subpage *prealloc,
struct extent_buffer **found_eb_ret)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
struct address_space *mapping = fs_info->btree_inode->i_mapping;
const unsigned long index = eb->start >> PAGE_SHIFT;
struct folio *existing_folio = NULL;
int ret;
ASSERT(found_eb_ret);
/* Caller should ensure the folio exists. */
ASSERT(eb->folios[i]);
retry:
ret = filemap_add_folio(mapping, eb->folios[i], index + i,
GFP_NOFS | __GFP_NOFAIL);
if (!ret)
goto finish;
existing_folio = filemap_lock_folio(mapping, index + i);
/* The page cache only exists for a very short time, just retry. */
if (IS_ERR(existing_folio)) {
existing_folio = NULL;
goto retry;
}
/* For now, we should only have single-page folios for btree inode. */
ASSERT(folio_nr_pages(existing_folio) == 1);
if (folio_size(existing_folio) != eb->folio_size) {
folio_unlock(existing_folio);
folio_put(existing_folio);
return -EAGAIN;
}
finish:
spin_lock(&mapping->i_private_lock);
if (existing_folio && fs_info->nodesize < PAGE_SIZE) {
/* We're going to reuse the existing page, can drop our folio now. */
__free_page(folio_page(eb->folios[i], 0));
eb->folios[i] = existing_folio;
} else if (existing_folio) {
struct extent_buffer *existing_eb;
existing_eb = grab_extent_buffer(fs_info,
folio_page(existing_folio, 0));
if (existing_eb) {
/* The extent buffer still exists, we can use it directly. */
*found_eb_ret = existing_eb;
spin_unlock(&mapping->i_private_lock);
folio_unlock(existing_folio);
folio_put(existing_folio);
return 1;
}
/* The extent buffer no longer exists, we can reuse the folio. */
__free_page(folio_page(eb->folios[i], 0));
eb->folios[i] = existing_folio;
}
eb->folio_size = folio_size(eb->folios[i]);
eb->folio_shift = folio_shift(eb->folios[i]);
/* Should not fail, as we have preallocated the memory. */
ret = attach_extent_buffer_folio(eb, eb->folios[i], prealloc);
ASSERT(!ret);
/*
* To inform we have an extra eb under allocation, so that
* detach_extent_buffer_page() won't release the folio private when the
* eb hasn't been inserted into radix tree yet.
*
* The ref will be decreased when the eb releases the page, in
* detach_extent_buffer_page(). Thus needs no special handling in the
* error path.
*/
btrfs_folio_inc_eb_refs(fs_info, eb->folios[i]);
spin_unlock(&mapping->i_private_lock);
return 0;
}
struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
u64 start, u64 owner_root, int level)
{
unsigned long len = fs_info->nodesize;
int num_folios;
int attached = 0;
struct extent_buffer *eb;
struct extent_buffer *existing_eb = NULL;
struct btrfs_subpage *prealloc = NULL;
u64 lockdep_owner = owner_root;
bool page_contig = true;
int uptodate = 1;
int ret;
if (check_eb_alignment(fs_info, start))
return ERR_PTR(-EINVAL);
#if BITS_PER_LONG == 32
if (start >= MAX_LFS_FILESIZE) {
btrfs_err_rl(fs_info,
"extent buffer %llu is beyond 32bit page cache limit", start);
btrfs_err_32bit_limit(fs_info);
return ERR_PTR(-EOVERFLOW);
}
if (start >= BTRFS_32BIT_EARLY_WARN_THRESHOLD)
btrfs_warn_32bit_limit(fs_info);
#endif
eb = find_extent_buffer(fs_info, start);
if (eb)
return eb;
eb = __alloc_extent_buffer(fs_info, start, len);
if (!eb)
return ERR_PTR(-ENOMEM);
/*
* The reloc trees are just snapshots, so we need them to appear to be
* just like any other fs tree WRT lockdep.
*/
if (lockdep_owner == BTRFS_TREE_RELOC_OBJECTID)
lockdep_owner = BTRFS_FS_TREE_OBJECTID;
btrfs_set_buffer_lockdep_class(lockdep_owner, eb, level);
/*
* Preallocate folio private for subpage case, so that we won't
* allocate memory with i_private_lock nor page lock hold.
*
* The memory will be freed by attach_extent_buffer_page() or freed
* manually if we exit earlier.
*/
if (fs_info->nodesize < PAGE_SIZE) {
prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA);
if (IS_ERR(prealloc)) {
ret = PTR_ERR(prealloc);
goto out;
}
}
reallocate:
/* Allocate all pages first. */
ret = alloc_eb_folio_array(eb, true);
if (ret < 0) {
btrfs_free_subpage(prealloc);
goto out;
}
num_folios = num_extent_folios(eb);
/* Attach all pages to the filemap. */
for (int i = 0; i < num_folios; i++) {
struct folio *folio;
ret = attach_eb_folio_to_filemap(eb, i, prealloc, &existing_eb);
if (ret > 0) {
ASSERT(existing_eb);
goto out;
}
/*
* TODO: Special handling for a corner case where the order of
* folios mismatch between the new eb and filemap.
*
* This happens when:
*
* - the new eb is using higher order folio
*
* - the filemap is still using 0-order folios for the range
* This can happen at the previous eb allocation, and we don't
* have higher order folio for the call.
*
* - the existing eb has already been freed
*
* In this case, we have to free the existing folios first, and
* re-allocate using the same order.
* Thankfully this is not going to happen yet, as we're still
* using 0-order folios.
*/
if (unlikely(ret == -EAGAIN)) {
ASSERT(0);
goto reallocate;
}
attached++;
/*
* Only after attach_eb_folio_to_filemap(), eb->folios[] is
* reliable, as we may choose to reuse the existing page cache
* and free the allocated page.
*/
folio = eb->folios[i];
WARN_ON(btrfs_folio_test_dirty(fs_info, folio, eb->start, eb->len));
/*
* Check if the current page is physically contiguous with previous eb
* page.
* At this stage, either we allocated a large folio, thus @i
* would only be 0, or we fall back to per-page allocation.
*/
if (i && folio_page(eb->folios[i - 1], 0) + 1 != folio_page(folio, 0))
page_contig = false;
if (!btrfs_folio_test_uptodate(fs_info, folio, eb->start, eb->len))
uptodate = 0;
/*
* We can't unlock the pages just yet since the extent buffer
* hasn't been properly inserted in the radix tree, this
* opens a race with btree_release_folio which can free a page
* while we are still filling in all pages for the buffer and
* we could crash.
*/
}
if (uptodate)
set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
/* All pages are physically contiguous, can skip cross page handling. */
if (page_contig)
eb->addr = folio_address(eb->folios[0]) + offset_in_page(eb->start);
again:
ret = radix_tree_preload(GFP_NOFS);
</