ceph: introduce ceph_process_folio_batch() method

First step of ceph_writepages_start() logic is
of finding the dirty memory folios and processing it.
This patch introduces ceph_process_folio_batch()
method that moves this logic into dedicated method.

The ceph_writepages_start() has this logic:

if (ceph_wbc.locked_pages == 0)
    lock_page(page);  /* first page */
else if (!trylock_page(page))
    break;

<skipped>

if (folio_test_writeback(folio) ||
    folio_test_private_2(folio) /* [DEPRECATED] */) {
      if (wbc->sync_mode == WB_SYNC_NONE) {
          doutc(cl, "%p under writeback\n", folio);
          folio_unlock(folio);
          continue;
      }
      doutc(cl, "waiting on writeback %p\n", folio);
      folio_wait_writeback(folio);
      folio_wait_private_2(folio); /* [DEPRECATED] */
}

The problem here that folio/page is locked here at first
and it is by set_page_writeback(page) later before
submitting the write request. The folio/page is unlocked
by writepages_finish() after finishing the write
request. It means that logic of checking folio_test_writeback()
and folio_wait_writeback() never works because page is locked
and it cannot be locked again until write request completion.
However, for majority of folios/pages the trylock_page()
is used. As a result, multiple threads can try to lock the same
folios/pages multiple times even if they are under writeback
already. It makes this logic more compute intensive than
it is necessary.

This patch changes this logic:

if (folio_test_writeback(folio) ||
    folio_test_private_2(folio) /* [DEPRECATED] */) {
      if (wbc->sync_mode == WB_SYNC_NONE) {
          doutc(cl, "%p under writeback\n", folio);
          folio_unlock(folio);
          continue;
      }
      doutc(cl, "waiting on writeback %p\n", folio);
      folio_wait_writeback(folio);
      folio_wait_private_2(folio); /* [DEPRECATED] */
}

if (ceph_wbc.locked_pages == 0)
    lock_page(page);  /* first page */
else if (!trylock_page(page))
    break;

This logic should exclude the ignoring of writeback
state of folios/pages.

Signed-off-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Link: https://lore.kernel.org/r/20250205000249.123054-3-slava@dubeyko.com
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Viacheslav Dubeyko 2025-02-04 16:02:47 -08:00 committed by Christian Brauner
parent f08068df4a
commit ce80b76dd3
No known key found for this signature in database
GPG key ID: 91C61BC06578DCA2

View file

@ -978,6 +978,27 @@ static void writepages_finish(struct ceph_osd_request *req)
ceph_dec_osd_stopping_blocker(fsc->mdsc);
}
static inline
bool is_forced_umount(struct address_space *mapping)
{
struct inode *inode = mapping->host;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = fsc->client;
if (ceph_inode_is_shutdown(inode)) {
if (ci->i_wrbuffer_ref > 0) {
pr_warn_ratelimited_client(cl,
"%llx.%llx %lld forced umount\n",
ceph_vinop(inode), ceph_ino(inode));
}
mapping_set_error(mapping, -EIO);
return true;
}
return false;
}
static inline
unsigned int ceph_define_write_size(struct address_space *mapping)
{
@ -1046,6 +1067,334 @@ void ceph_init_writeback_ctl(struct address_space *mapping,
ceph_wbc->data_pages = NULL;
}
static inline
int ceph_define_writeback_range(struct address_space *mapping,
struct writeback_control *wbc,
struct ceph_writeback_ctl *ceph_wbc)
{
struct inode *inode = mapping->host;
struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = fsc->client;
/* find oldest snap context with dirty data */
ceph_wbc->snapc = get_oldest_context(inode, ceph_wbc, NULL);
if (!ceph_wbc->snapc) {
/* hmm, why does writepages get called when there
is no dirty data? */
doutc(cl, " no snap context with dirty data?\n");
return -ENODATA;
}
doutc(cl, " oldest snapc is %p seq %lld (%d snaps)\n",
ceph_wbc->snapc, ceph_wbc->snapc->seq,
ceph_wbc->snapc->num_snaps);
ceph_wbc->should_loop = false;
if (ceph_wbc->head_snapc && ceph_wbc->snapc != ceph_wbc->last_snapc) {
/* where to start/end? */
if (wbc->range_cyclic) {
ceph_wbc->index = ceph_wbc->start_index;
ceph_wbc->end = -1;
if (ceph_wbc->index > 0)
ceph_wbc->should_loop = true;
doutc(cl, " cyclic, start at %lu\n", ceph_wbc->index);
} else {
ceph_wbc->index = wbc->range_start >> PAGE_SHIFT;
ceph_wbc->end = wbc->range_end >> PAGE_SHIFT;
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
ceph_wbc->range_whole = true;
doutc(cl, " not cyclic, %lu to %lu\n",
ceph_wbc->index, ceph_wbc->end);
}
} else if (!ceph_wbc->head_snapc) {
/* Do not respect wbc->range_{start,end}. Dirty pages
* in that range can be associated with newer snapc.
* They are not writeable until we write all dirty pages
* associated with 'snapc' get written */
if (ceph_wbc->index > 0)
ceph_wbc->should_loop = true;
doutc(cl, " non-head snapc, range whole\n");
}
ceph_put_snap_context(ceph_wbc->last_snapc);
ceph_wbc->last_snapc = ceph_wbc->snapc;
return 0;
}
static inline
bool has_writeback_done(struct ceph_writeback_ctl *ceph_wbc)
{
return ceph_wbc->done && ceph_wbc->index > ceph_wbc->end;
}
static inline
bool can_next_page_be_processed(struct ceph_writeback_ctl *ceph_wbc,
unsigned index)
{
return index < ceph_wbc->nr_folios &&
ceph_wbc->locked_pages < ceph_wbc->max_pages;
}
static
int ceph_check_page_before_write(struct address_space *mapping,
struct writeback_control *wbc,
struct ceph_writeback_ctl *ceph_wbc,
struct folio *folio)
{
struct inode *inode = mapping->host;
struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = fsc->client;
struct ceph_snap_context *pgsnapc;
struct page *page = &folio->page;
/* only dirty pages, or our accounting breaks */
if (unlikely(!PageDirty(page)) || unlikely(page->mapping != mapping)) {
doutc(cl, "!dirty or !mapping %p\n", page);
return -ENODATA;
}
/* only if matching snap context */
pgsnapc = page_snap_context(page);
if (pgsnapc != ceph_wbc->snapc) {
doutc(cl, "page snapc %p %lld != oldest %p %lld\n",
pgsnapc, pgsnapc->seq,
ceph_wbc->snapc, ceph_wbc->snapc->seq);
if (!ceph_wbc->should_loop && !ceph_wbc->head_snapc &&
wbc->sync_mode != WB_SYNC_NONE)
ceph_wbc->should_loop = true;
return -ENODATA;
}
if (page_offset(page) >= ceph_wbc->i_size) {
doutc(cl, "folio at %lu beyond eof %llu\n",
folio->index, ceph_wbc->i_size);
if ((ceph_wbc->size_stable ||
folio_pos(folio) >= i_size_read(inode)) &&
folio_clear_dirty_for_io(folio))
folio_invalidate(folio, 0, folio_size(folio));
return -ENODATA;
}
if (ceph_wbc->strip_unit_end &&
(page->index > ceph_wbc->strip_unit_end)) {
doutc(cl, "end of strip unit %p\n", page);
return -E2BIG;
}
return 0;
}
static inline
void __ceph_allocate_page_array(struct ceph_writeback_ctl *ceph_wbc,
unsigned int max_pages)
{
ceph_wbc->pages = kmalloc_array(max_pages,
sizeof(*ceph_wbc->pages),
GFP_NOFS);
if (!ceph_wbc->pages) {
ceph_wbc->from_pool = true;
ceph_wbc->pages = mempool_alloc(ceph_wb_pagevec_pool, GFP_NOFS);
BUG_ON(!ceph_wbc->pages);
}
}
static inline
void ceph_allocate_page_array(struct address_space *mapping,
struct ceph_writeback_ctl *ceph_wbc,
struct page *page)
{
struct inode *inode = mapping->host;
struct ceph_inode_info *ci = ceph_inode(inode);
u64 objnum;
u64 objoff;
u32 xlen;
/* prepare async write request */
ceph_wbc->offset = (u64)page_offset(page);
ceph_calc_file_object_mapping(&ci->i_layout,
ceph_wbc->offset, ceph_wbc->wsize,
&objnum, &objoff, &xlen);
ceph_wbc->num_ops = 1;
ceph_wbc->strip_unit_end = page->index + ((xlen - 1) >> PAGE_SHIFT);
BUG_ON(ceph_wbc->pages);
ceph_wbc->max_pages = calc_pages_for(0, (u64)xlen);
__ceph_allocate_page_array(ceph_wbc, ceph_wbc->max_pages);
ceph_wbc->len = 0;
}
static inline
bool is_page_index_contiguous(struct ceph_writeback_ctl *ceph_wbc,
struct page *page)
{
return page->index == (ceph_wbc->offset + ceph_wbc->len) >> PAGE_SHIFT;
}
static inline
bool is_num_ops_too_big(struct ceph_writeback_ctl *ceph_wbc)
{
return ceph_wbc->num_ops >=
(ceph_wbc->from_pool ? CEPH_OSD_SLAB_OPS : CEPH_OSD_MAX_OPS);
}
static inline
bool is_write_congestion_happened(struct ceph_fs_client *fsc)
{
return atomic_long_inc_return(&fsc->writeback_count) >
CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb);
}
static inline
int ceph_move_dirty_page_in_page_array(struct address_space *mapping,
struct writeback_control *wbc,
struct ceph_writeback_ctl *ceph_wbc,
struct page *page)
{
struct inode *inode = mapping->host;
struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = fsc->client;
struct page **pages = ceph_wbc->pages;
unsigned int index = ceph_wbc->locked_pages;
gfp_t gfp_flags = ceph_wbc->locked_pages ? GFP_NOWAIT : GFP_NOFS;
if (IS_ENCRYPTED(inode)) {
pages[index] = fscrypt_encrypt_pagecache_blocks(page,
PAGE_SIZE,
0,
gfp_flags);
if (IS_ERR(pages[index])) {
if (PTR_ERR(pages[index]) == -EINVAL) {
pr_err_client(cl, "inode->i_blkbits=%hhu\n",
inode->i_blkbits);
}
/* better not fail on first page! */
BUG_ON(ceph_wbc->locked_pages == 0);
pages[index] = NULL;
return PTR_ERR(pages[index]);
}
} else {
pages[index] = page;
}
ceph_wbc->locked_pages++;
return 0;
}
static
int ceph_process_folio_batch(struct address_space *mapping,
struct writeback_control *wbc,
struct ceph_writeback_ctl *ceph_wbc)
{
struct inode *inode = mapping->host;
struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = fsc->client;
struct folio *folio = NULL;
struct page *page = NULL;
unsigned i;
int rc = 0;
for (i = 0; can_next_page_be_processed(ceph_wbc, i); i++) {
folio = ceph_wbc->fbatch.folios[i];
if (!folio)
continue;
page = &folio->page;
doutc(cl, "? %p idx %lu, folio_test_writeback %#x, "
"folio_test_dirty %#x, folio_test_locked %#x\n",
page, page->index, folio_test_writeback(folio),
folio_test_dirty(folio),
folio_test_locked(folio));
if (folio_test_writeback(folio) ||
folio_test_private_2(folio) /* [DEPRECATED] */) {
doutc(cl, "waiting on writeback %p\n", folio);
folio_wait_writeback(folio);
folio_wait_private_2(folio); /* [DEPRECATED] */
continue;
}
if (ceph_wbc->locked_pages == 0)
lock_page(page); /* first page */
else if (!trylock_page(page))
break;
rc = ceph_check_page_before_write(mapping, wbc,
ceph_wbc, folio);
if (rc == -ENODATA) {
rc = 0;
unlock_page(page);
ceph_wbc->fbatch.folios[i] = NULL;
continue;
} else if (rc == -E2BIG) {
rc = 0;
unlock_page(page);
ceph_wbc->fbatch.folios[i] = NULL;
break;
}
if (!clear_page_dirty_for_io(page)) {
doutc(cl, "%p !clear_page_dirty_for_io\n", page);
unlock_page(page);
ceph_wbc->fbatch.folios[i] = NULL;
continue;
}
/*
* We have something to write. If this is
* the first locked page this time through,
* calculate max possible write size and
* allocate a page array
*/
if (ceph_wbc->locked_pages == 0) {
ceph_allocate_page_array(mapping, ceph_wbc, page);
} else if (!is_page_index_contiguous(ceph_wbc, page)) {
if (is_num_ops_too_big(ceph_wbc)) {
redirty_page_for_writepage(wbc, page);
unlock_page(page);
break;
}
ceph_wbc->num_ops++;
ceph_wbc->offset = (u64)page_offset(page);
ceph_wbc->len = 0;
}
/* note position of first page in fbatch */
doutc(cl, "%llx.%llx will write page %p idx %lu\n",
ceph_vinop(inode), page, page->index);
fsc->write_congested = is_write_congestion_happened(fsc);
rc = ceph_move_dirty_page_in_page_array(mapping, wbc,
ceph_wbc, page);
if (rc) {
redirty_page_for_writepage(wbc, page);
unlock_page(page);
break;
}
ceph_wbc->fbatch.folios[i] = NULL;
ceph_wbc->len += thp_size(page);
}
ceph_wbc->processed_in_fbatch = i;
return rc;
}
/*
* initiate async writeback
*/
@ -1057,7 +1406,6 @@ static int ceph_writepages_start(struct address_space *mapping,
struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = fsc->client;
struct ceph_vino vino = ceph_vino(inode);
struct ceph_snap_context *pgsnapc;
struct ceph_writeback_ctl ceph_wbc;
struct ceph_osd_request *req = NULL;
int rc = 0;
@ -1071,235 +1419,49 @@ static int ceph_writepages_start(struct address_space *mapping,
wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
(wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
if (ceph_inode_is_shutdown(inode)) {
if (ci->i_wrbuffer_ref > 0) {
pr_warn_ratelimited_client(cl,
"%llx.%llx %lld forced umount\n",
ceph_vinop(inode), ceph_ino(inode));
}
mapping_set_error(mapping, -EIO);
return -EIO; /* we're in a forced umount, don't write! */
if (is_forced_umount(mapping)) {
/* we're in a forced umount, don't write! */
return -EIO;
}
ceph_init_writeback_ctl(mapping, wbc, &ceph_wbc);
retry:
/* find oldest snap context with dirty data */
ceph_wbc.snapc = get_oldest_context(inode, &ceph_wbc, NULL);
if (!ceph_wbc.snapc) {
rc = ceph_define_writeback_range(mapping, wbc, &ceph_wbc);
if (rc == -ENODATA) {
/* hmm, why does writepages get called when there
is no dirty data? */
doutc(cl, " no snap context with dirty data?\n");
rc = 0;
goto out;
}
doutc(cl, " oldest snapc is %p seq %lld (%d snaps)\n",
ceph_wbc.snapc, ceph_wbc.snapc->seq,
ceph_wbc.snapc->num_snaps);
ceph_wbc.should_loop = false;
if (ceph_wbc.head_snapc && ceph_wbc.snapc != ceph_wbc.last_snapc) {
/* where to start/end? */
if (wbc->range_cyclic) {
ceph_wbc.index = ceph_wbc.start_index;
ceph_wbc.end = -1;
if (ceph_wbc.index > 0)
ceph_wbc.should_loop = true;
doutc(cl, " cyclic, start at %lu\n", ceph_wbc.index);
} else {
ceph_wbc.index = wbc->range_start >> PAGE_SHIFT;
ceph_wbc.end = wbc->range_end >> PAGE_SHIFT;
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
ceph_wbc.range_whole = true;
doutc(cl, " not cyclic, %lu to %lu\n",
ceph_wbc.index, ceph_wbc.end);
}
} else if (!ceph_wbc.head_snapc) {
/* Do not respect wbc->range_{start,end}. Dirty pages
* in that range can be associated with newer snapc.
* They are not writeable until we write all dirty pages
* associated with 'snapc' get written */
if (ceph_wbc.index > 0)
ceph_wbc.should_loop = true;
doutc(cl, " non-head snapc, range whole\n");
}
if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
tag_pages_for_writeback(mapping, ceph_wbc.index, ceph_wbc.end);
ceph_put_snap_context(ceph_wbc.last_snapc);
ceph_wbc.last_snapc = ceph_wbc.snapc;
while (!ceph_wbc.done && ceph_wbc.index <= ceph_wbc.end) {
while (!has_writeback_done(&ceph_wbc)) {
unsigned i;
struct page *page;
ceph_wbc.locked_pages = 0;
ceph_wbc.max_pages = ceph_wbc.wsize >> PAGE_SHIFT;
get_more_pages:
ceph_folio_batch_reinit(&ceph_wbc);
ceph_wbc.nr_folios = filemap_get_folios_tag(mapping,
&ceph_wbc.index,
ceph_wbc.end,
ceph_wbc.tag,
&ceph_wbc.fbatch);
doutc(cl, "pagevec_lookup_range_tag got %d\n",
ceph_wbc.nr_folios);
doutc(cl, "pagevec_lookup_range_tag for tag %#x got %d\n",
ceph_wbc.tag, ceph_wbc.nr_folios);
if (!ceph_wbc.nr_folios && !ceph_wbc.locked_pages)
break;
for (i = 0; i < ceph_wbc.nr_folios &&
ceph_wbc.locked_pages < ceph_wbc.max_pages; i++) {
struct folio *folio = ceph_wbc.fbatch.folios[i];
page = &folio->page;
doutc(cl, "? %p idx %lu\n", page, page->index);
if (ceph_wbc.locked_pages == 0)
lock_page(page); /* first page */
else if (!trylock_page(page))
break;
/* only dirty pages, or our accounting breaks */
if (unlikely(!PageDirty(page)) ||
unlikely(page->mapping != mapping)) {
doutc(cl, "!dirty or !mapping %p\n", page);
unlock_page(page);
continue;
}
/* only if matching snap context */
pgsnapc = page_snap_context(page);
if (pgsnapc != ceph_wbc.snapc) {
doutc(cl, "page snapc %p %lld != oldest %p %lld\n",
pgsnapc, pgsnapc->seq,
ceph_wbc.snapc, ceph_wbc.snapc->seq);
if (!ceph_wbc.should_loop &&
!ceph_wbc.head_snapc &&
wbc->sync_mode != WB_SYNC_NONE)
ceph_wbc.should_loop = true;
unlock_page(page);
continue;
}
if (page_offset(page) >= ceph_wbc.i_size) {
doutc(cl, "folio at %lu beyond eof %llu\n",
folio->index, ceph_wbc.i_size);
if ((ceph_wbc.size_stable ||
folio_pos(folio) >= i_size_read(inode)) &&
folio_clear_dirty_for_io(folio))
folio_invalidate(folio, 0,
folio_size(folio));
folio_unlock(folio);
continue;
}
if (ceph_wbc.strip_unit_end &&
(page->index > ceph_wbc.strip_unit_end)) {
doutc(cl, "end of strip unit %p\n", page);
unlock_page(page);
break;
}
if (folio_test_writeback(folio) ||
folio_test_private_2(folio) /* [DEPRECATED] */) {
if (wbc->sync_mode == WB_SYNC_NONE) {
doutc(cl, "%p under writeback\n", folio);
folio_unlock(folio);
continue;
}
doutc(cl, "waiting on writeback %p\n", folio);
folio_wait_writeback(folio);
folio_wait_private_2(folio); /* [DEPRECATED] */
}
if (!clear_page_dirty_for_io(page)) {
doutc(cl, "%p !clear_page_dirty_for_io\n", page);
unlock_page(page);
continue;
}
/*
* We have something to write. If this is
* the first locked page this time through,
* calculate max possinle write size and
* allocate a page array
*/
if (ceph_wbc.locked_pages == 0) {
u64 objnum;
u64 objoff;
u32 xlen;
/* prepare async write request */
ceph_wbc.offset = (u64)page_offset(page);
ceph_calc_file_object_mapping(&ci->i_layout,
ceph_wbc.offset,
ceph_wbc.wsize,
&objnum, &objoff,
&xlen);
ceph_wbc.len = xlen;
ceph_wbc.num_ops = 1;
ceph_wbc.strip_unit_end = page->index +
((ceph_wbc.len - 1) >> PAGE_SHIFT);
BUG_ON(ceph_wbc.pages);
ceph_wbc.max_pages =
calc_pages_for(0, (u64)ceph_wbc.len);
ceph_wbc.pages = kmalloc_array(ceph_wbc.max_pages,
sizeof(*ceph_wbc.pages),
GFP_NOFS);
if (!ceph_wbc.pages) {
ceph_wbc.from_pool = true;
ceph_wbc.pages =
mempool_alloc(ceph_wb_pagevec_pool,
GFP_NOFS);
BUG_ON(!ceph_wbc.pages);
}
ceph_wbc.len = 0;
} else if (page->index !=
(ceph_wbc.offset + ceph_wbc.len) >> PAGE_SHIFT) {
if (ceph_wbc.num_ops >=
(ceph_wbc.from_pool ? CEPH_OSD_SLAB_OPS :
CEPH_OSD_MAX_OPS)) {
redirty_page_for_writepage(wbc, page);
unlock_page(page);
break;
}
ceph_wbc.num_ops++;
ceph_wbc.offset = (u64)page_offset(page);
ceph_wbc.len = 0;
}
/* note position of first page in fbatch */
doutc(cl, "%llx.%llx will write page %p idx %lu\n",
ceph_vinop(inode), page, page->index);
if (atomic_long_inc_return(&fsc->writeback_count) >
CONGESTION_ON_THRESH(
fsc->mount_options->congestion_kb))
fsc->write_congested = true;
if (IS_ENCRYPTED(inode)) {
ceph_wbc.pages[ceph_wbc.locked_pages] =
fscrypt_encrypt_pagecache_blocks(page,
PAGE_SIZE, 0,
ceph_wbc.locked_pages ?
GFP_NOWAIT : GFP_NOFS);
if (IS_ERR(ceph_wbc.pages[ceph_wbc.locked_pages])) {
if (PTR_ERR(ceph_wbc.pages[ceph_wbc.locked_pages]) == -EINVAL)
pr_err_client(cl,
"inode->i_blkbits=%hhu\n",
inode->i_blkbits);
/* better not fail on first page! */
BUG_ON(ceph_wbc.locked_pages == 0);
ceph_wbc.pages[ceph_wbc.locked_pages] = NULL;
redirty_page_for_writepage(wbc, page);
unlock_page(page);
break;
}
++ceph_wbc.locked_pages;
} else {
ceph_wbc.pages[ceph_wbc.locked_pages++] = page;
}
ceph_wbc.fbatch.folios[i] = NULL;
ceph_wbc.len += thp_size(page);
}
rc = ceph_process_folio_batch(mapping, wbc, &ceph_wbc);
if (rc)
goto release_folios;
/* did we get anything? */
if (!ceph_wbc.locked_pages)