original development tree for Linux kernel GTP module; now long in mainline.
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/* Storage object read/write
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/file.h>
#include "internal.h"
/*
* detect wake up events generated by the unlocking of pages in which we're
* interested
* - we use this to detect read completion of backing pages
* - the caller holds the waitqueue lock
*/
static int cachefiles_read_waiter(wait_queue_t *wait, unsigned mode,
int sync, void *_key)
{
struct cachefiles_one_read *monitor =
container_of(wait, struct cachefiles_one_read, monitor);
struct cachefiles_object *object;
struct wait_bit_key *key = _key;
struct page *page = wait->private;
ASSERT(key);
_enter("{%lu},%u,%d,{%p,%u}",
monitor->netfs_page->index, mode, sync,
key->flags, key->bit_nr);
if (key->flags != &page->flags ||
key->bit_nr != PG_locked)
return 0;
_debug("--- monitor %p %lx ---", page, page->flags);
if (!PageUptodate(page) && !PageError(page)) {
/* unlocked, not uptodate and not erronous? */
_debug("page probably truncated");
}
/* remove from the waitqueue */
list_del(&wait->task_list);
/* move onto the action list and queue for FS-Cache thread pool */
ASSERT(monitor->op);
object = container_of(monitor->op->op.object,
struct cachefiles_object, fscache);
spin_lock(&object->work_lock);
list_add_tail(&monitor->op_link, &monitor->op->to_do);
spin_unlock(&object->work_lock);
fscache_enqueue_retrieval(monitor->op);
return 0;
}
/*
* handle a probably truncated page
* - check to see if the page is still relevant and reissue the read if
* possible
* - return -EIO on error, -ENODATA if the page is gone, -EINPROGRESS if we
* must wait again and 0 if successful
*/
static int cachefiles_read_reissue(struct cachefiles_object *object,
struct cachefiles_one_read *monitor)
{
struct address_space *bmapping = object->backer->d_inode->i_mapping;
struct page *backpage = monitor->back_page, *backpage2;
int ret;
kenter("{ino=%lx},{%lx,%lx}",
object->backer->d_inode->i_ino,
backpage->index, backpage->flags);
/* skip if the page was truncated away completely */
if (backpage->mapping != bmapping) {
kleave(" = -ENODATA [mapping]");
return -ENODATA;
}
backpage2 = find_get_page(bmapping, backpage->index);
if (!backpage2) {
kleave(" = -ENODATA [gone]");
return -ENODATA;
}
if (backpage != backpage2) {
put_page(backpage2);
kleave(" = -ENODATA [different]");
return -ENODATA;
}
/* the page is still there and we already have a ref on it, so we don't
* need a second */
put_page(backpage2);
INIT_LIST_HEAD(&monitor->op_link);
add_page_wait_queue(backpage, &monitor->monitor);
if (trylock_page(backpage)) {
ret = -EIO;
if (PageError(backpage))
goto unlock_discard;
ret = 0;
if (PageUptodate(backpage))
goto unlock_discard;
kdebug("reissue read");
ret = bmapping->a_ops->readpage(NULL, backpage);
if (ret < 0)
goto unlock_discard;
}
/* but the page may have been read before the monitor was installed, so
* the monitor may miss the event - so we have to ensure that we do get
* one in such a case */
if (trylock_page(backpage)) {
_debug("jumpstart %p {%lx}", backpage, backpage->flags);
unlock_page(backpage);
}
/* it'll reappear on the todo list */
kleave(" = -EINPROGRESS");
return -EINPROGRESS;
unlock_discard:
unlock_page(backpage);
spin_lock_irq(&object->work_lock);
list_del(&monitor->op_link);
spin_unlock_irq(&object->work_lock);
kleave(" = %d", ret);
return ret;
}
/*
* copy data from backing pages to netfs pages to complete a read operation
* - driven by FS-Cache's thread pool
*/
static void cachefiles_read_copier(struct fscache_operation *_op)
{
struct cachefiles_one_read *monitor;
struct cachefiles_object *object;
struct fscache_retrieval *op;
struct pagevec pagevec;
int error, max;
op = container_of(_op, struct fscache_retrieval, op);
object = container_of(op->op.object,
struct cachefiles_object, fscache);
_enter("{ino=%lu}", object->backer->d_inode->i_ino);
pagevec_init(&pagevec, 0);
max = 8;
spin_lock_irq(&object->work_lock);
while (!list_empty(&op->to_do)) {
monitor = list_entry(op->to_do.next,
struct cachefiles_one_read, op_link);
list_del(&monitor->op_link);
spin_unlock_irq(&object->work_lock);
_debug("- copy {%lu}", monitor->back_page->index);
recheck:
if (PageUptodate(monitor->back_page)) {
copy_highpage(monitor->netfs_page, monitor->back_page);
fscache_mark_page_cached(monitor->op,
monitor->netfs_page);
error = 0;
} else if (!PageError(monitor->back_page)) {
/* the page has probably been truncated */
error = cachefiles_read_reissue(object, monitor);
if (error == -EINPROGRESS)
goto next;
goto recheck;
} else {
cachefiles_io_error_obj(
object,
"Readpage failed on backing file %lx",
(unsigned long) monitor->back_page->flags);
error = -EIO;
}
page_cache_release(monitor->back_page);
fscache_end_io(op, monitor->netfs_page, error);
page_cache_release(monitor->netfs_page);
fscache_put_retrieval(op);
kfree(monitor);
next:
/* let the thread pool have some air occasionally */
max--;
if (max < 0 || need_resched()) {
if (!list_empty(&op->to_do))
fscache_enqueue_retrieval(op);
_leave(" [maxed out]");
return;
}
spin_lock_irq(&object->work_lock);
}
spin_unlock_irq(&object->work_lock);
_leave("");
}
/*
* read the corresponding page to the given set from the backing file
* - an uncertain page is simply discarded, to be tried again another time
*/
static int cachefiles_read_backing_file_one(struct cachefiles_object *object,
struct fscache_retrieval *op,
struct page *netpage,
struct pagevec *pagevec)
{
struct cachefiles_one_read *monitor;
struct address_space *bmapping;
struct page *newpage, *backpage;
int ret;
_enter("");
pagevec_reinit(pagevec);
_debug("read back %p{%lu,%d}",
netpage, netpage->index, page_count(netpage));
monitor = kzalloc(sizeof(*monitor), GFP_KERNEL);
if (!monitor)
goto nomem;
monitor->netfs_page = netpage;
monitor->op = fscache_get_retrieval(op);
init_waitqueue_func_entry(&monitor->monitor, cachefiles_read_waiter);
/* attempt to get hold of the backing page */
bmapping = object->backer->d_inode->i_mapping;
newpage = NULL;
for (;;) {
backpage = find_get_page(bmapping, netpage->index);
if (backpage)
goto backing_page_already_present;
if (!newpage) {
newpage = page_cache_alloc_cold(bmapping);
if (!newpage)
goto nomem_monitor;
}
ret = add_to_page_cache(newpage, bmapping,
netpage->index, GFP_KERNEL);
if (ret == 0)
goto installed_new_backing_page;
if (ret != -EEXIST)
goto nomem_page;
}
/* we've installed a new backing page, so now we need to add it
* to the LRU list and start it reading */
installed_new_backing_page:
_debug("- new %p", newpage);
backpage = newpage;
newpage = NULL;
page_cache_get(backpage);
pagevec_add(pagevec, backpage);
__pagevec_lru_add_file(pagevec);
read_backing_page:
ret = bmapping->a_ops->readpage(NULL, backpage);
if (ret < 0)
goto read_error;
/* set the monitor to transfer the data across */
monitor_backing_page:
_debug("- monitor add");
/* install the monitor */
page_cache_get(monitor->netfs_page);
page_cache_get(backpage);
monitor->back_page = backpage;
monitor->monitor.private = backpage;
add_page_wait_queue(backpage, &monitor->monitor);
monitor = NULL;
/* but the page may have been read before the monitor was installed, so
* the monitor may miss the event - so we have to ensure that we do get
* one in such a case */
if (trylock_page(backpage)) {
_debug("jumpstart %p {%lx}", backpage, backpage->flags);
unlock_page(backpage);
}
goto success;
/* if the backing page is already present, it can be in one of
* three states: read in progress, read failed or read okay */
backing_page_already_present:
_debug("- present");
if (newpage) {
page_cache_release(newpage);
newpage = NULL;
}
if (PageError(backpage))
goto io_error;
if (PageUptodate(backpage))
goto backing_page_already_uptodate;
if (!trylock_page(backpage))
goto monitor_backing_page;
_debug("read %p {%lx}", backpage, backpage->flags);
goto read_backing_page;
/* the backing page is already up to date, attach the netfs
* page to the pagecache and LRU and copy the data across */
backing_page_already_uptodate:
_debug("- uptodate");
fscache_mark_page_cached(op, netpage);
copy_highpage(netpage, backpage);
fscache_end_io(op, netpage, 0);
success:
_debug("success");
ret = 0;
out:
if (backpage)
page_cache_release(backpage);
if (monitor) {
fscache_put_retrieval(monitor->op);
kfree(monitor);
}
_leave(" = %d", ret);
return ret;
read_error:
_debug("read error %d", ret);
if (ret == -ENOMEM)
goto out;
io_error:
cachefiles_io_error_obj(object, "Page read error on backing file");
ret = -ENOBUFS;
goto out;
nomem_page:
page_cache_release(newpage);
nomem_monitor:
fscache_put_retrieval(monitor->op);
kfree(monitor);
nomem:
_leave(" = -ENOMEM");
return -ENOMEM;
}
/*
* read a page from the cache or allocate a block in which to store it
* - cache withdrawal is prevented by the caller
* - returns -EINTR if interrupted
* - returns -ENOMEM if ran out of memory
* - returns -ENOBUFS if no buffers can be made available
* - returns -ENOBUFS if page is beyond EOF
* - if the page is backed by a block in the cache:
* - a read will be started which will call the callback on completion
* - 0 will be returned
* - else if the page is unbacked:
* - the metadata will be retained
* - -ENODATA will be returned
*/
int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct pagevec pagevec;
struct inode *inode;
sector_t block0, block;
unsigned shift;
int ret;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("{%p},{%lx},,,", object, page->index);
if (!object->backer)
return -ENOBUFS;
inode = object->backer->d_inode;
ASSERT(S_ISREG(inode->i_mode));
ASSERT(inode->i_mapping->a_ops->bmap);
ASSERT(inode->i_mapping->a_ops->readpages);
/* calculate the shift required to use bmap */
if (inode->i_sb->s_blocksize > PAGE_SIZE)
return -ENOBUFS;
shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
op->op.flags |= FSCACHE_OP_ASYNC;
op->op.processor = cachefiles_read_copier;
pagevec_init(&pagevec, 0);
/* we assume the absence or presence of the first block is a good
* enough indication for the page as a whole
* - TODO: don't use bmap() for this as it is _not_ actually good
* enough for this as it doesn't indicate errors, but it's all we've
* got for the moment
*/
block0 = page->index;
block0 <<= shift;
block = inode->i_mapping->a_ops->bmap(inode->i_mapping, block0);
_debug("%llx -> %llx",
(unsigned long long) block0,
(unsigned long long) block);
if (block) {
/* submit the apparently valid page to the backing fs to be
* read from disk */
ret = cachefiles_read_backing_file_one(object, op, page,
&pagevec);
} else if (cachefiles_has_space(cache, 0, 1) == 0) {
/* there's space in the cache we can use */
fscache_mark_page_cached(op, page);
ret = -ENODATA;
} else {
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* read the corresponding pages to the given set from the backing file
* - any uncertain pages are simply discarded, to be tried again another time
*/
static int cachefiles_read_backing_file(struct cachefiles_object *object,
struct fscache_retrieval *op,
struct list_head *list)
{
struct cachefiles_one_read *monitor = NULL;
struct address_space *bmapping = object->backer->d_inode->i_mapping;
struct pagevec lru_pvec;
struct page *newpage = NULL, *netpage, *_n, *backpage = NULL;
int ret = 0;
_enter("");
pagevec_init(&lru_pvec, 0);
list_for_each_entry_safe(netpage, _n, list, lru) {
list_del(&netpage->lru);
_debug("read back %p{%lu,%d}",
netpage, netpage->index, page_count(netpage));
if (!monitor) {
monitor = kzalloc(sizeof(*monitor), GFP_KERNEL);
if (!monitor)
goto nomem;
monitor->op = fscache_get_retrieval(op);
init_waitqueue_func_entry(&monitor->monitor,
cachefiles_read_waiter);
}
for (;;) {
backpage = find_get_page(bmapping, netpage->index);
if (backpage)
goto backing_page_already_present;
if (!newpage) {
newpage = page_cache_alloc_cold(bmapping);
if (!newpage)
goto nomem;
}
ret = add_to_page_cache(newpage, bmapping,
netpage->index, GFP_KERNEL);
if (ret == 0)
goto installed_new_backing_page;
if (ret != -EEXIST)
goto nomem;
}
/* we've installed a new backing page, so now we need to add it
* to the LRU list and start it reading */
installed_new_backing_page:
_debug("- new %p", newpage);
backpage = newpage;
newpage = NULL;
page_cache_get(backpage);
if (!pagevec_add(&lru_pvec, backpage))
__pagevec_lru_add_file(&lru_pvec);
reread_backing_page:
ret = bmapping->a_ops->readpage(NULL, backpage);
if (ret < 0)
goto read_error;
/* add the netfs page to the pagecache and LRU, and set the
* monitor to transfer the data across */
monitor_backing_page:
_debug("- monitor add");
ret = add_to_page_cache(netpage, op->mapping, netpage->index,
GFP_KERNEL);
if (ret < 0) {
if (ret == -EEXIST) {
page_cache_release(netpage);
continue;
}
goto nomem;
}
page_cache_get(netpage);
if (!pagevec_add(&lru_pvec, netpage))
__pagevec_lru_add_file(&lru_pvec);
/* install a monitor */
page_cache_get(netpage);
monitor->netfs_page = netpage;
page_cache_get(backpage);
monitor->back_page = backpage;
monitor->monitor.private = backpage;
add_page_wait_queue(backpage, &monitor->monitor);
monitor = NULL;
/* but the page may have been read before the monitor was
* installed, so the monitor may miss the event - so we have to
* ensure that we do get one in such a case */
if (trylock_page(backpage)) {
_debug("2unlock %p {%lx}", backpage, backpage->flags);
unlock_page(backpage);
}
page_cache_release(backpage);
backpage = NULL;
page_cache_release(netpage);
netpage = NULL;
continue;
/* if the backing page is already present, it can be in one of
* three states: read in progress, read failed or read okay */
backing_page_already_present:
_debug("- present %p", backpage);
if (PageError(backpage))
goto io_error;
if (PageUptodate(backpage))
goto backing_page_already_uptodate;
_debug("- not ready %p{%lx}", backpage, backpage->flags);
if (!trylock_page(backpage))
goto monitor_backing_page;
if (PageError(backpage)) {
_debug("error %lx", backpage->flags);
unlock_page(backpage);
goto io_error;
}
if (PageUptodate(backpage))
goto backing_page_already_uptodate_unlock;
/* we've locked a page that's neither up to date nor erroneous,
* so we need to attempt to read it again */
goto reread_backing_page;
/* the backing page is already up to date, attach the netfs
* page to the pagecache and LRU and copy the data across */
backing_page_already_uptodate_unlock:
_debug("uptodate %lx", backpage->flags);
unlock_page(backpage);
backing_page_already_uptodate:
_debug("- uptodate");
ret = add_to_page_cache(netpage, op->mapping, netpage->index,
GFP_KERNEL);
if (ret < 0) {
if (ret == -EEXIST) {
page_cache_release(netpage);
continue;
}
goto nomem;
}
copy_highpage(netpage, backpage);
page_cache_release(backpage);
backpage = NULL;
fscache_mark_page_cached(op, netpage);
page_cache_get(netpage);
if (!pagevec_add(&lru_pvec, netpage))
__pagevec_lru_add_file(&lru_pvec);
/* the netpage is unlocked and marked up to date here */
fscache_end_io(op, netpage, 0);
page_cache_release(netpage);
netpage = NULL;
continue;
}
netpage = NULL;
_debug("out");
out:
/* tidy up */
pagevec_lru_add_file(&lru_pvec);
if (newpage)
page_cache_release(newpage);
if (netpage)
page_cache_release(netpage);
if (backpage)
page_cache_release(backpage);
if (monitor) {
fscache_put_retrieval(op);
kfree(monitor);
}
list_for_each_entry_safe(netpage, _n, list, lru) {
list_del(&netpage->lru);
page_cache_release(netpage);
}
_leave(" = %d", ret);
return ret;
nomem:
_debug("nomem");
ret = -ENOMEM;
goto out;
read_error:
_debug("read error %d", ret);
if (ret == -ENOMEM)
goto out;
io_error:
cachefiles_io_error_obj(object, "Page read error on backing file");
ret = -ENOBUFS;
goto out;
}
/*
* read a list of pages from the cache or allocate blocks in which to store
* them
*/
int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct list_head backpages;
struct pagevec pagevec;
struct inode *inode;
struct page *page, *_n;
unsigned shift, nrbackpages;
int ret, ret2, space;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("{OBJ%x,%d},,%d,,",
object->fscache.debug_id, atomic_read(&op->op.usage),
*nr_pages);
if (!object->backer)
return -ENOBUFS;
space = 1;
if (cachefiles_has_space(cache, 0, *nr_pages) < 0)
space = 0;
inode = object->backer->d_inode;
ASSERT(S_ISREG(inode->i_mode));
ASSERT(inode->i_mapping->a_ops->bmap);
ASSERT(inode->i_mapping->a_ops->readpages);
/* calculate the shift required to use bmap */
if (inode->i_sb->s_blocksize > PAGE_SIZE)
return -ENOBUFS;
shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
pagevec_init(&pagevec, 0);
op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
op->op.flags |= FSCACHE_OP_ASYNC;
op->op.processor = cachefiles_read_copier;
INIT_LIST_HEAD(&backpages);
nrbackpages = 0;
ret = space ? -ENODATA : -ENOBUFS;
list_for_each_entry_safe(page, _n, pages, lru) {
sector_t block0, block;
/* we assume the absence or presence of the first block is a
* good enough indication for the page as a whole
* - TODO: don't use bmap() for this as it is _not_ actually
* good enough for this as it doesn't indicate errors, but
* it's all we've got for the moment
*/
block0 = page->index;
block0 <<= shift;
block = inode->i_mapping->a_ops->bmap(inode->i_mapping,
block0);
_debug("%llx -> %llx",
(unsigned long long) block0,
(unsigned long long) block);
if (block) {
/* we have data - add it to the list to give to the
* backing fs */
list_move(&page->lru, &backpages);
(*nr_pages)--;
nrbackpages++;
} else if (space && pagevec_add(&pagevec, page) == 0) {
fscache_mark_pages_cached(op, &pagevec);
ret = -ENODATA;
}
}
if (pagevec_count(&pagevec) > 0)
fscache_mark_pages_cached(op, &pagevec);
if (list_empty(pages))
ret = 0;
/* submit the apparently valid pages to the backing fs to be read from
* disk */
if (nrbackpages > 0) {
ret2 = cachefiles_read_backing_file(object, op, &backpages);
if (ret2 == -ENOMEM || ret2 == -EINTR)
ret = ret2;
}
_leave(" = %d [nr=%u%s]",
ret, *nr_pages, list_empty(pages) ? " empty" : "");
return ret;
}
/*
* allocate a block in the cache in which to store a page
* - cache withdrawal is prevented by the caller
* - returns -EINTR if interrupted
* - returns -ENOMEM if ran out of memory
* - returns -ENOBUFS if no buffers can be made available
* - returns -ENOBUFS if page is beyond EOF
* - otherwise:
* - the metadata will be retained
* - 0 will be returned
*/
int cachefiles_allocate_page(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
int ret;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("%p,{%lx},", object, page->index);
ret = cachefiles_has_space(cache, 0, 1);
if (ret == 0)
fscache_mark_page_cached(op, page);
else
ret = -ENOBUFS;
_leave(" = %d", ret);
return ret;
}
/*
* allocate blocks in the cache in which to store a set of pages
* - cache withdrawal is prevented by the caller
* - returns -EINTR if interrupted
* - returns -ENOMEM if ran out of memory
* - returns -ENOBUFS if some buffers couldn't be made available
* - returns -ENOBUFS if some pages are beyond EOF
* - otherwise:
* - -ENODATA will be returned
* - metadata will be retained for any page marked
*/
int cachefiles_allocate_pages(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
struct pagevec pagevec;
struct page *page;
int ret;
object = container_of(op->op.object,
struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("%p,,,%d,", object, *nr_pages);
ret = cachefiles_has_space(cache, 0, *nr_pages);
if (ret == 0) {
pagevec_init(&pagevec, 0);
list_for_each_entry(page, pages, lru) {
if (pagevec_add(&pagevec, page) == 0)
fscache_mark_pages_cached(op, &pagevec);
}
if (pagevec_count(&pagevec) > 0)
fscache_mark_pages_cached(op, &pagevec);
ret = -ENODATA;
} else {
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* request a page be stored in the cache
* - cache withdrawal is prevented by the caller
* - this request may be ignored if there's no cache block available, in which
* case -ENOBUFS will be returned
* - if the op is in progress, 0 will be returned
*/
int cachefiles_write_page(struct fscache_storage *op, struct page *page)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
mm_segment_t old_fs;
struct file *file;
struct path path;
loff_t pos, eof;
size_t len;
void *data;
int ret;
ASSERT(op != NULL);
ASSERT(page != NULL);
object = container_of(op->op.object,
struct cachefiles_object, fscache);
_enter("%p,%p{%lx},,,", object, page, page->index);
if (!object->backer) {
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
ASSERT(S_ISREG(object->backer->d_inode->i_mode));
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
/* write the page to the backing filesystem and let it store it in its
* own time */
path.mnt = cache->mnt;
path.dentry = object->backer;
file = dentry_open(&path, O_RDWR | O_LARGEFILE, cache->cache_cred);
if (IS_ERR(file)) {
ret = PTR_ERR(file);
} else {
ret = -EIO;
if (file->f_op->write) {
pos = (loff_t) page->index << PAGE_SHIFT;
/* we mustn't write more data than we have, so we have
* to beware of a partial page at EOF */
eof = object->fscache.store_limit_l;
len = PAGE_SIZE;
if (eof & ~PAGE_MASK) {
ASSERTCMP(pos, <, eof);
if (eof - pos < PAGE_SIZE) {
_debug("cut short %llx to %llx",
pos, eof);
len = eof - pos;
ASSERTCMP(pos + len, ==, eof);
}
}
data = kmap(page);
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = file->f_op->write(
file, (const void __user *) data, len, &pos);
set_fs(old_fs);
kunmap(page);
if (ret != len)
ret = -EIO;
}
fput(file);
}
if (ret < 0) {
if (ret == -EIO)
cachefiles_io_error_obj(
object, "Write page to backing file failed");
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* detach a backing block from a page
* - cache withdrawal is prevented by the caller
*/
void cachefiles_uncache_page(struct fscache_object *_object, struct page *page)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache;
object = container_of(_object, struct cachefiles_object, fscache);
cache = container_of(object->fscache.cache,
struct cachefiles_cache, cache);
_enter("%p,{%lu}", object, page->index);
spin_unlock(&object->fscache.cookie->lock);
}