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addr.c
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addr.c
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// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>
#include <linux/backing-dev.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/writeback.h> /* generic_writepages */
#include <linux/slab.h>
#include <linux/pagevec.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/signal.h>
#include <linux/iversion.h>
#include "super.h"
#include "mds_client.h"
#include "cache.h"
#include <linux/ceph/osd_client.h>
#include <linux/ceph/striper.h>
/*
* Ceph address space ops.
*
* There are a few funny things going on here.
*
* The page->private field is used to reference a struct
* ceph_snap_context for _every_ dirty page. This indicates which
* snapshot the page was logically dirtied in, and thus which snap
* context needs to be associated with the osd write during writeback.
*
* Similarly, struct ceph_inode_info maintains a set of counters to
* count dirty pages on the inode. In the absence of snapshots,
* i_wrbuffer_ref == i_wrbuffer_ref_head == the dirty page count.
*
* When a snapshot is taken (that is, when the client receives
* notification that a snapshot was taken), each inode with caps and
* with dirty pages (dirty pages implies there is a cap) gets a new
* ceph_cap_snap in the i_cap_snaps list (which is sorted in ascending
* order, new snaps go to the tail). The i_wrbuffer_ref_head count is
* moved to capsnap->dirty. (Unless a sync write is currently in
* progress. In that case, the capsnap is said to be "pending", new
* writes cannot start, and the capsnap isn't "finalized" until the
* write completes (or fails) and a final size/mtime for the inode for
* that snap can be settled upon.) i_wrbuffer_ref_head is reset to 0.
*
* On writeback, we must submit writes to the osd IN SNAP ORDER. So,
* we look for the first capsnap in i_cap_snaps and write out pages in
* that snap context _only_. Then we move on to the next capsnap,
* eventually reaching the "live" or "head" context (i.e., pages that
* are not yet snapped) and are writing the most recently dirtied
* pages.
*
* Invalidate and so forth must take care to ensure the dirty page
* accounting is preserved.
*/
#define CONGESTION_ON_THRESH(congestion_kb) (congestion_kb >> (PAGE_SHIFT-10))
#define CONGESTION_OFF_THRESH(congestion_kb) \
(CONGESTION_ON_THRESH(congestion_kb) - \
(CONGESTION_ON_THRESH(congestion_kb) >> 2))
static inline struct ceph_snap_context *page_snap_context(struct page *page)
{
if (PagePrivate(page))
return (void *)page->private;
return NULL;
}
/*
* Dirty a page. Optimistically adjust accounting, on the assumption
* that we won't race with invalidate. If we do, readjust.
*/
static int ceph_set_page_dirty(struct page *page)
{
struct address_space *mapping = page->mapping;
struct inode *inode;
struct ceph_inode_info *ci;
struct ceph_snap_context *snapc;
int ret;
if (unlikely(!mapping))
return !TestSetPageDirty(page);
if (PageDirty(page)) {
dout("%p set_page_dirty %p idx %lu -- already dirty\n",
mapping->host, page, page->index);
BUG_ON(!PagePrivate(page));
return 0;
}
inode = mapping->host;
ci = ceph_inode(inode);
/* dirty the head */
spin_lock(&ci->i_ceph_lock);
BUG_ON(ci->i_wr_ref == 0); // caller should hold Fw reference
if (__ceph_have_pending_cap_snap(ci)) {
struct ceph_cap_snap *capsnap =
list_last_entry(&ci->i_cap_snaps,
struct ceph_cap_snap,
ci_item);
snapc = ceph_get_snap_context(capsnap->context);
capsnap->dirty_pages++;
} else {
BUG_ON(!ci->i_head_snapc);
snapc = ceph_get_snap_context(ci->i_head_snapc);
++ci->i_wrbuffer_ref_head;
}
if (ci->i_wrbuffer_ref == 0)
ihold(inode);
++ci->i_wrbuffer_ref;
dout("%p set_page_dirty %p idx %lu head %d/%d -> %d/%d "
"snapc %p seq %lld (%d snaps)\n",
mapping->host, page, page->index,
ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref_head-1,
ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
snapc, snapc->seq, snapc->num_snaps);
spin_unlock(&ci->i_ceph_lock);
/*
* Reference snap context in page->private. Also set
* PagePrivate so that we get invalidatepage callback.
*/
BUG_ON(PagePrivate(page));
page->private = (unsigned long)snapc;
SetPagePrivate(page);
ret = __set_page_dirty_nobuffers(page);
WARN_ON(!PageLocked(page));
WARN_ON(!page->mapping);
return ret;
}
/*
* If we are truncating the full page (i.e. offset == 0), adjust the
* dirty page counters appropriately. Only called if there is private
* data on the page.
*/
static void ceph_invalidatepage(struct page *page, unsigned int offset,
unsigned int length)
{
struct inode *inode;
struct ceph_inode_info *ci;
struct ceph_snap_context *snapc = page_snap_context(page);
inode = page->mapping->host;
ci = ceph_inode(inode);
if (offset != 0 || length != PAGE_SIZE) {
dout("%p invalidatepage %p idx %lu partial dirty page %u~%u\n",
inode, page, page->index, offset, length);
return;
}
ceph_invalidate_fscache_page(inode, page);
WARN_ON(!PageLocked(page));
if (!PagePrivate(page))
return;
ClearPageChecked(page);
dout("%p invalidatepage %p idx %lu full dirty page\n",
inode, page, page->index);
ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
ceph_put_snap_context(snapc);
page->private = 0;
ClearPagePrivate(page);
}
static int ceph_releasepage(struct page *page, gfp_t g)
{
dout("%p releasepage %p idx %lu (%sdirty)\n", page->mapping->host,
page, page->index, PageDirty(page) ? "" : "not ");
/* Can we release the page from the cache? */
if (!ceph_release_fscache_page(page, g))
return 0;
return !PagePrivate(page);
}
/*
* read a single page, without unlocking it.
*/
static int ceph_do_readpage(struct file *filp, struct page *page)
{
struct inode *inode = file_inode(filp);
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
int err = 0;
u64 off = page_offset(page);
u64 len = PAGE_SIZE;
if (off >= i_size_read(inode)) {
zero_user_segment(page, 0, PAGE_SIZE);
SetPageUptodate(page);
return 0;
}
if (ci->i_inline_version != CEPH_INLINE_NONE) {
/*
* Uptodate inline data should have been added
* into page cache while getting Fcr caps.
*/
if (off == 0)
return -EINVAL;
zero_user_segment(page, 0, PAGE_SIZE);
SetPageUptodate(page);
return 0;
}
err = ceph_readpage_from_fscache(inode, page);
if (err == 0)
return -EINPROGRESS;
dout("readpage inode %p file %p page %p index %lu\n",
inode, filp, page, page->index);
err = ceph_osdc_readpages(&fsc->client->osdc, ceph_vino(inode),
&ci->i_layout, off, &len,
ci->i_truncate_seq, ci->i_truncate_size,
&page, 1, 0);
if (err == -ENOENT)
err = 0;
if (err < 0) {
SetPageError(page);
ceph_fscache_readpage_cancel(inode, page);
if (err == -EBLACKLISTED)
fsc->blacklisted = true;
goto out;
}
if (err < PAGE_SIZE)
/* zero fill remainder of page */
zero_user_segment(page, err, PAGE_SIZE);
else
flush_dcache_page(page);
SetPageUptodate(page);
ceph_readpage_to_fscache(inode, page);
out:
return err < 0 ? err : 0;
}
static int ceph_readpage(struct file *filp, struct page *page)
{
int r = ceph_do_readpage(filp, page);
if (r != -EINPROGRESS)
unlock_page(page);
else
r = 0;
return r;
}
/*
* Finish an async read(ahead) op.
*/
static void finish_read(struct ceph_osd_request *req)
{
struct inode *inode = req->r_inode;
struct ceph_osd_data *osd_data;
int rc = req->r_result <= 0 ? req->r_result : 0;
int bytes = req->r_result >= 0 ? req->r_result : 0;
int num_pages;
int i;
dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
if (rc == -EBLACKLISTED)
ceph_inode_to_client(inode)->blacklisted = true;
/* unlock all pages, zeroing any data we didn't read */
osd_data = osd_req_op_extent_osd_data(req, 0);
BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
num_pages = calc_pages_for((u64)osd_data->alignment,
(u64)osd_data->length);
for (i = 0; i < num_pages; i++) {
struct page *page = osd_data->pages[i];
if (rc < 0 && rc != -ENOENT) {
ceph_fscache_readpage_cancel(inode, page);
goto unlock;
}
if (bytes < (int)PAGE_SIZE) {
/* zero (remainder of) page */
int s = bytes < 0 ? 0 : bytes;
zero_user_segment(page, s, PAGE_SIZE);
}
dout("finish_read %p uptodate %p idx %lu\n", inode, page,
page->index);
flush_dcache_page(page);
SetPageUptodate(page);
ceph_readpage_to_fscache(inode, page);
unlock:
unlock_page(page);
put_page(page);
bytes -= PAGE_SIZE;
}
kfree(osd_data->pages);
}
/*
* start an async read(ahead) operation. return nr_pages we submitted
* a read for on success, or negative error code.
*/
static int start_read(struct inode *inode, struct ceph_rw_context *rw_ctx,
struct list_head *page_list, int max)
{
struct ceph_osd_client *osdc =
&ceph_inode_to_client(inode)->client->osdc;
struct ceph_inode_info *ci = ceph_inode(inode);
struct page *page = lru_to_page(page_list);
struct ceph_vino vino;
struct ceph_osd_request *req;
u64 off;
u64 len;
int i;
struct page **pages;
pgoff_t next_index;
int nr_pages = 0;
int got = 0;
int ret = 0;
if (!rw_ctx) {
/* caller of readpages does not hold buffer and read caps
* (fadvise, madvise and readahead cases) */
int want = CEPH_CAP_FILE_CACHE;
ret = ceph_try_get_caps(inode, CEPH_CAP_FILE_RD, want,
true, &got);
if (ret < 0) {
dout("start_read %p, error getting cap\n", inode);
} else if (!(got & want)) {
dout("start_read %p, no cache cap\n", inode);
ret = 0;
}
if (ret <= 0) {
if (got)
ceph_put_cap_refs(ci, got);
while (!list_empty(page_list)) {
page = lru_to_page(page_list);
list_del(&page->lru);
put_page(page);
}
return ret;
}
}
off = (u64) page_offset(page);
/* count pages */
next_index = page->index;
list_for_each_entry_reverse(page, page_list, lru) {
if (page->index != next_index)
break;
nr_pages++;
next_index++;
if (max && nr_pages == max)
break;
}
len = nr_pages << PAGE_SHIFT;
dout("start_read %p nr_pages %d is %lld~%lld\n", inode, nr_pages,
off, len);
vino = ceph_vino(inode);
req = ceph_osdc_new_request(osdc, &ci->i_layout, vino, off, &len,
0, 1, CEPH_OSD_OP_READ,
CEPH_OSD_FLAG_READ, NULL,
ci->i_truncate_seq, ci->i_truncate_size,
false);
if (IS_ERR(req)) {
ret = PTR_ERR(req);
goto out;
}
/* build page vector */
nr_pages = calc_pages_for(0, len);
pages = kmalloc_array(nr_pages, sizeof(*pages), GFP_KERNEL);
if (!pages) {
ret = -ENOMEM;
goto out_put;
}
for (i = 0; i < nr_pages; ++i) {
page = list_entry(page_list->prev, struct page, lru);
BUG_ON(PageLocked(page));
list_del(&page->lru);
dout("start_read %p adding %p idx %lu\n", inode, page,
page->index);
if (add_to_page_cache_lru(page, &inode->i_data, page->index,
GFP_KERNEL)) {
ceph_fscache_uncache_page(inode, page);
put_page(page);
dout("start_read %p add_to_page_cache failed %p\n",
inode, page);
nr_pages = i;
if (nr_pages > 0) {
len = nr_pages << PAGE_SHIFT;
osd_req_op_extent_update(req, 0, len);
break;
}
goto out_pages;
}
pages[i] = page;
}
osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0, false, false);
req->r_callback = finish_read;
req->r_inode = inode;
dout("start_read %p starting %p %lld~%lld\n", inode, req, off, len);
ret = ceph_osdc_start_request(osdc, req, false);
if (ret < 0)
goto out_pages;
ceph_osdc_put_request(req);
/* After adding locked pages to page cache, the inode holds cache cap.
* So we can drop our cap refs. */
if (got)
ceph_put_cap_refs(ci, got);
return nr_pages;
out_pages:
for (i = 0; i < nr_pages; ++i) {
ceph_fscache_readpage_cancel(inode, pages[i]);
unlock_page(pages[i]);
}
ceph_put_page_vector(pages, nr_pages, false);
out_put:
ceph_osdc_put_request(req);
out:
if (got)
ceph_put_cap_refs(ci, got);
return ret;
}
/*
* Read multiple pages. Leave pages we don't read + unlock in page_list;
* the caller (VM) cleans them up.
*/
static int ceph_readpages(struct file *file, struct address_space *mapping,
struct list_head *page_list, unsigned nr_pages)
{
struct inode *inode = file_inode(file);
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
struct ceph_file_info *fi = file->private_data;
struct ceph_rw_context *rw_ctx;
int rc = 0;
int max = 0;
if (ceph_inode(inode)->i_inline_version != CEPH_INLINE_NONE)
return -EINVAL;
rc = ceph_readpages_from_fscache(mapping->host, mapping, page_list,
&nr_pages);
if (rc == 0)
goto out;
rw_ctx = ceph_find_rw_context(fi);
max = fsc->mount_options->rsize >> PAGE_SHIFT;
dout("readpages %p file %p ctx %p nr_pages %d max %d\n",
inode, file, rw_ctx, nr_pages, max);
while (!list_empty(page_list)) {
rc = start_read(inode, rw_ctx, page_list, max);
if (rc < 0)
goto out;
}
out:
ceph_fscache_readpages_cancel(inode, page_list);
dout("readpages %p file %p ret %d\n", inode, file, rc);
return rc;
}
struct ceph_writeback_ctl
{
loff_t i_size;
u64 truncate_size;
u32 truncate_seq;
bool size_stable;
bool head_snapc;
};
/*
* Get ref for the oldest snapc for an inode with dirty data... that is, the
* only snap context we are allowed to write back.
*/
static struct ceph_snap_context *
get_oldest_context(struct inode *inode, struct ceph_writeback_ctl *ctl,
struct ceph_snap_context *page_snapc)
{
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_snap_context *snapc = NULL;
struct ceph_cap_snap *capsnap = NULL;
spin_lock(&ci->i_ceph_lock);
list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
dout(" cap_snap %p snapc %p has %d dirty pages\n", capsnap,
capsnap->context, capsnap->dirty_pages);
if (!capsnap->dirty_pages)
continue;
/* get i_size, truncate_{seq,size} for page_snapc? */
if (snapc && capsnap->context != page_snapc)
continue;
if (ctl) {
if (capsnap->writing) {
ctl->i_size = i_size_read(inode);
ctl->size_stable = false;
} else {
ctl->i_size = capsnap->size;
ctl->size_stable = true;
}
ctl->truncate_size = capsnap->truncate_size;
ctl->truncate_seq = capsnap->truncate_seq;
ctl->head_snapc = false;
}
if (snapc)
break;
snapc = ceph_get_snap_context(capsnap->context);
if (!page_snapc ||
page_snapc == snapc ||
page_snapc->seq > snapc->seq)
break;
}
if (!snapc && ci->i_wrbuffer_ref_head) {
snapc = ceph_get_snap_context(ci->i_head_snapc);
dout(" head snapc %p has %d dirty pages\n",
snapc, ci->i_wrbuffer_ref_head);
if (ctl) {
ctl->i_size = i_size_read(inode);
ctl->truncate_size = ci->i_truncate_size;
ctl->truncate_seq = ci->i_truncate_seq;
ctl->size_stable = false;
ctl->head_snapc = true;
}
}
spin_unlock(&ci->i_ceph_lock);
return snapc;
}
static u64 get_writepages_data_length(struct inode *inode,
struct page *page, u64 start)
{
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_snap_context *snapc = page_snap_context(page);
struct ceph_cap_snap *capsnap = NULL;
u64 end = i_size_read(inode);
if (snapc != ci->i_head_snapc) {
bool found = false;
spin_lock(&ci->i_ceph_lock);
list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
if (capsnap->context == snapc) {
if (!capsnap->writing)
end = capsnap->size;
found = true;
break;
}
}
spin_unlock(&ci->i_ceph_lock);
WARN_ON(!found);
}
if (end > page_offset(page) + PAGE_SIZE)
end = page_offset(page) + PAGE_SIZE;
return end > start ? end - start : 0;
}
/*
* Write a single page, but leave the page locked.
*
* If we get a write error, mark the mapping for error, but still adjust the
* dirty page accounting (i.e., page is no longer dirty).
*/
static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
{
struct inode *inode;
struct ceph_inode_info *ci;
struct ceph_fs_client *fsc;
struct ceph_snap_context *snapc, *oldest;
loff_t page_off = page_offset(page);
int err, len = PAGE_SIZE;
struct ceph_writeback_ctl ceph_wbc;
dout("writepage %p idx %lu\n", page, page->index);
inode = page->mapping->host;
ci = ceph_inode(inode);
fsc = ceph_inode_to_client(inode);
/* verify this is a writeable snap context */
snapc = page_snap_context(page);
if (!snapc) {
dout("writepage %p page %p not dirty?\n", inode, page);
return 0;
}
oldest = get_oldest_context(inode, &ceph_wbc, snapc);
if (snapc->seq > oldest->seq) {
dout("writepage %p page %p snapc %p not writeable - noop\n",
inode, page, snapc);
/* we should only noop if called by kswapd */
WARN_ON(!(current->flags & PF_MEMALLOC));
ceph_put_snap_context(oldest);
redirty_page_for_writepage(wbc, page);
return 0;
}
ceph_put_snap_context(oldest);
/* is this a partial page at end of file? */
if (page_off >= ceph_wbc.i_size) {
dout("%p page eof %llu\n", page, ceph_wbc.i_size);
page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
return 0;
}
if (ceph_wbc.i_size < page_off + len)
len = ceph_wbc.i_size - page_off;
dout("writepage %p page %p index %lu on %llu~%u snapc %p seq %lld\n",
inode, page, page->index, page_off, len, snapc, snapc->seq);
if (atomic_long_inc_return(&fsc->writeback_count) >
CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
set_page_writeback(page);
err = ceph_osdc_writepages(&fsc->client->osdc, ceph_vino(inode),
&ci->i_layout, snapc, page_off, len,
ceph_wbc.truncate_seq,
ceph_wbc.truncate_size,
&inode->i_mtime, &page, 1);
if (err < 0) {
struct writeback_control tmp_wbc;
if (!wbc)
wbc = &tmp_wbc;
if (err == -ERESTARTSYS) {
/* killed by SIGKILL */
dout("writepage interrupted page %p\n", page);
redirty_page_for_writepage(wbc, page);
end_page_writeback(page);
return err;
}
if (err == -EBLACKLISTED)
fsc->blacklisted = true;
dout("writepage setting page/mapping error %d %p\n",
err, page);
mapping_set_error(&inode->i_data, err);
wbc->pages_skipped++;
} else {
dout("writepage cleaned page %p\n", page);
err = 0; /* vfs expects us to return 0 */
}
page->private = 0;
ClearPagePrivate(page);
end_page_writeback(page);
ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
ceph_put_snap_context(snapc); /* page's reference */
if (atomic_long_dec_return(&fsc->writeback_count) <
CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
return err;
}
static int ceph_writepage(struct page *page, struct writeback_control *wbc)
{
int err;
struct inode *inode = page->mapping->host;
BUG_ON(!inode);
ihold(inode);
err = writepage_nounlock(page, wbc);
if (err == -ERESTARTSYS) {
/* direct memory reclaimer was killed by SIGKILL. return 0
* to prevent caller from setting mapping/page error */
err = 0;
}
unlock_page(page);
iput(inode);
return err;
}
/*
* async writeback completion handler.
*
* If we get an error, set the mapping error bit, but not the individual
* page error bits.
*/
static void writepages_finish(struct ceph_osd_request *req)
{
struct inode *inode = req->r_inode;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_osd_data *osd_data;
struct page *page;
int num_pages, total_pages = 0;
int i, j;
int rc = req->r_result;
struct ceph_snap_context *snapc = req->r_snapc;
struct address_space *mapping = inode->i_mapping;
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
bool remove_page;
dout("writepages_finish %p rc %d\n", inode, rc);
if (rc < 0) {
mapping_set_error(mapping, rc);
ceph_set_error_write(ci);
if (rc == -EBLACKLISTED)
fsc->blacklisted = true;
} else {
ceph_clear_error_write(ci);
}
/*
* We lost the cache cap, need to truncate the page before
* it is unlocked, otherwise we'd truncate it later in the
* page truncation thread, possibly losing some data that
* raced its way in
*/
remove_page = !(ceph_caps_issued(ci) &
(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO));
/* clean all pages */
for (i = 0; i < req->r_num_ops; i++) {
if (req->r_ops[i].op != CEPH_OSD_OP_WRITE)
break;
osd_data = osd_req_op_extent_osd_data(req, i);
BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
num_pages = calc_pages_for((u64)osd_data->alignment,
(u64)osd_data->length);
total_pages += num_pages;
for (j = 0; j < num_pages; j++) {
page = osd_data->pages[j];
BUG_ON(!page);
WARN_ON(!PageUptodate(page));
if (atomic_long_dec_return(&fsc->writeback_count) <
CONGESTION_OFF_THRESH(
fsc->mount_options->congestion_kb))
clear_bdi_congested(inode_to_bdi(inode),
BLK_RW_ASYNC);
ceph_put_snap_context(page_snap_context(page));
page->private = 0;
ClearPagePrivate(page);
dout("unlocking %p\n", page);
end_page_writeback(page);
if (remove_page)
generic_error_remove_page(inode->i_mapping,
page);
unlock_page(page);
}
dout("writepages_finish %p wrote %llu bytes cleaned %d pages\n",
inode, osd_data->length, rc >= 0 ? num_pages : 0);
release_pages(osd_data->pages, num_pages);
}
ceph_put_wrbuffer_cap_refs(ci, total_pages, snapc);
osd_data = osd_req_op_extent_osd_data(req, 0);
if (osd_data->pages_from_pool)
mempool_free(osd_data->pages,
ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
else
kfree(osd_data->pages);
ceph_osdc_put_request(req);
}
/*
* initiate async writeback
*/
static int ceph_writepages_start(struct address_space *mapping,
struct writeback_control *wbc)
{
struct inode *inode = mapping->host;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
struct ceph_vino vino = ceph_vino(inode);
pgoff_t index, start_index, end = -1;
struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
struct pagevec pvec;
int rc = 0;
unsigned int wsize = i_blocksize(inode);
struct ceph_osd_request *req = NULL;
struct ceph_writeback_ctl ceph_wbc;
bool should_loop, range_whole = false;
bool done = false;
dout("writepages_start %p (mode=%s)\n", inode,
wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
(wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD"));
if (READ_ONCE(fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
if (ci->i_wrbuffer_ref > 0) {
pr_warn_ratelimited(
"writepage_start %p %lld forced umount\n",
inode, ceph_ino(inode));
}
mapping_set_error(mapping, -EIO);
return -EIO; /* we're in a forced umount, don't write! */
}
if (fsc->mount_options->wsize < wsize)
wsize = fsc->mount_options->wsize;
pagevec_init(&pvec);
start_index = wbc->range_cyclic ? mapping->writeback_index : 0;
index = start_index;
retry:
/* find oldest snap context with dirty data */
snapc = get_oldest_context(inode, &ceph_wbc, NULL);
if (!snapc) {
/* hmm, why does writepages get called when there
is no dirty data? */
dout(" no snap context with dirty data?\n");
goto out;
}
dout(" oldest snapc is %p seq %lld (%d snaps)\n",
snapc, snapc->seq, snapc->num_snaps);
should_loop = false;
if (ceph_wbc.head_snapc && snapc != last_snapc) {
/* where to start/end? */
if (wbc->range_cyclic) {
index = start_index;
end = -1;
if (index > 0)
should_loop = true;
dout(" cyclic, start at %lu\n", index);
} 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 = true;
dout(" not cyclic, %lu to %lu\n", index, 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 (index > 0)
should_loop = true;
dout(" non-head snapc, range whole\n");
}
ceph_put_snap_context(last_snapc);
last_snapc = snapc;
while (!done && index <= end) {
int num_ops = 0, op_idx;
unsigned i, pvec_pages, max_pages, locked_pages = 0;
struct page **pages = NULL, **data_pages;
mempool_t *pool = NULL; /* Becomes non-null if mempool used */
struct page *page;
pgoff_t strip_unit_end = 0;
u64 offset = 0, len = 0;
max_pages = wsize >> PAGE_SHIFT;
get_more_pages:
pvec_pages = pagevec_lookup_range_nr_tag(&pvec, mapping, &index,
end, PAGECACHE_TAG_DIRTY,
max_pages - locked_pages);
dout("pagevec_lookup_range_tag got %d\n", pvec_pages);
if (!pvec_pages && !locked_pages)
break;
for (i = 0; i < pvec_pages && locked_pages < max_pages; i++) {
page = pvec.pages[i];
dout("? %p idx %lu\n", page, page->index);
if (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)) {
dout("!dirty or !mapping %p\n", page);
unlock_page(page);
continue;
}
/* only if matching snap context */
pgsnapc = page_snap_context(page);
if (pgsnapc != snapc) {
dout("page snapc %p %lld != oldest %p %lld\n",
pgsnapc, pgsnapc->seq, snapc, snapc->seq);
if (!should_loop &&
!ceph_wbc.head_snapc &&
wbc->sync_mode != WB_SYNC_NONE)
should_loop = true;
unlock_page(page);
continue;
}
if (page_offset(page) >= ceph_wbc.i_size) {
dout("%p page eof %llu\n",
page, ceph_wbc.i_size);
if ((ceph_wbc.size_stable ||
page_offset(page) >= i_size_read(inode)) &&
clear_page_dirty_for_io(page))
mapping->a_ops->invalidatepage(page,
0, PAGE_SIZE);
unlock_page(page);
continue;
}
if (strip_unit_end && (page->index > strip_unit_end)) {
dout("end of strip unit %p\n", page);
unlock_page(page);
break;
}
if (PageWriteback(page)) {
if (wbc->sync_mode == WB_SYNC_NONE) {
dout("%p under writeback\n", page);
unlock_page(page);
continue;
}
dout("waiting on writeback %p\n", page);
wait_on_page_writeback(page);
}
if (!clear_page_dirty_for_io(page)) {
dout("%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 (locked_pages == 0) {
u64 objnum;
u64 objoff;
u32 xlen;
/* prepare async write request */
offset = (u64)page_offset(page);
ceph_calc_file_object_mapping(&ci->i_layout,
offset, wsize,
&objnum, &objoff,
&xlen);
len = xlen;
num_ops = 1;
strip_unit_end = page->index +
((len - 1) >> PAGE_SHIFT);
BUG_ON(pages);
max_pages = calc_pages_for(0, (u64)len);
pages = kmalloc_array(max_pages,
sizeof(*pages),
GFP_NOFS);
if (!pages) {
pool = fsc->wb_pagevec_pool;
pages = mempool_alloc(pool, GFP_NOFS);
BUG_ON(!pages);
}
len = 0;
} else if (page->index !=
(offset + len) >> PAGE_SHIFT) {
if (num_ops >= (pool ? CEPH_OSD_SLAB_OPS :
CEPH_OSD_MAX_OPS)) {
redirty_page_for_writepage(wbc, page);
unlock_page(page);
break;
}
num_ops++;
offset = (u64)page_offset(page);
len = 0;
}
/* note position of first page in pvec */
dout("%p will write page %p idx %lu\n",
inode, page, page->index);
if (atomic_long_inc_return(&fsc->writeback_count) >
CONGESTION_ON_THRESH(
fsc->mount_options->congestion_kb)) {
set_bdi_congested(inode_to_bdi(inode),
BLK_RW_ASYNC);
}
pages[locked_pages++] = page;
pvec.pages[i] = NULL;
len += PAGE_SIZE;
}