| /* 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 <linux/swap.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_entry_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 fscache_retrieval *op = monitor->op; |
| 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->entry); |
| |
| /* move onto the action list and queue for FS-Cache thread pool */ |
| ASSERT(op); |
| |
| /* We need to temporarily bump the usage count as we don't own a ref |
| * here otherwise cachefiles_read_copier() may free the op between the |
| * monitor being enqueued on the op->to_do list and the op getting |
| * enqueued on the work queue. |
| */ |
| fscache_get_retrieval(op); |
| |
| object = container_of(op->op.object, struct cachefiles_object, fscache); |
| spin_lock(&object->work_lock); |
| list_add_tail(&monitor->op_link, &op->to_do); |
| fscache_enqueue_retrieval(op); |
| spin_unlock(&object->work_lock); |
| |
| fscache_put_retrieval(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 = d_backing_inode(object->backer)->i_mapping; |
| struct page *backpage = monitor->back_page, *backpage2; |
| int ret; |
| |
| _enter("{ino=%lx},{%lx,%lx}", |
| d_backing_inode(object->backer)->i_ino, |
| backpage->index, backpage->flags); |
| |
| /* skip if the page was truncated away completely */ |
| if (backpage->mapping != bmapping) { |
| _leave(" = -ENODATA [mapping]"); |
| return -ENODATA; |
| } |
| |
| backpage2 = find_get_page(bmapping, backpage->index); |
| if (!backpage2) { |
| _leave(" = -ENODATA [gone]"); |
| return -ENODATA; |
| } |
| |
| if (backpage != backpage2) { |
| put_page(backpage2); |
| _leave(" = -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; |
| |
| _debug("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 */ |
| _leave(" = -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); |
| _leave(" = %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; |
| int error, max; |
| |
| op = container_of(_op, struct fscache_retrieval, op); |
| object = container_of(op->op.object, |
| struct cachefiles_object, fscache); |
| |
| _enter("{ino=%lu}", d_backing_inode(object->backer)->i_ino); |
| |
| 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 (test_bit(FSCACHE_COOKIE_INVALIDATING, |
| &object->fscache.cookie->flags)) { |
| error = -ESTALE; |
| } else 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; |
| } |
| |
| put_page(monitor->back_page); |
| |
| fscache_end_io(op, monitor->netfs_page, error); |
| put_page(monitor->netfs_page); |
| fscache_retrieval_complete(op, 1); |
| 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 cachefiles_one_read *monitor; |
| struct address_space *bmapping; |
| struct page *newpage, *backpage; |
| int ret; |
| |
| _enter(""); |
| |
| _debug("read back %p{%lu,%d}", |
| netpage, netpage->index, page_count(netpage)); |
| |
| monitor = kzalloc(sizeof(*monitor), cachefiles_gfp); |
| 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 = d_backing_inode(object->backer)->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(cachefiles_gfp); |
| if (!newpage) |
| goto nomem_monitor; |
| } |
| |
| ret = add_to_page_cache_lru(newpage, bmapping, |
| netpage->index, cachefiles_gfp); |
| 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 start |
| * it reading */ |
| installed_new_backing_page: |
| _debug("- new %p", newpage); |
| |
| backpage = newpage; |
| newpage = NULL; |
| |
| 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 */ |
| get_page(monitor->netfs_page); |
| get_page(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) { |
| put_page(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); |
| fscache_retrieval_complete(op, 1); |
| |
| success: |
| _debug("success"); |
| ret = 0; |
| |
| out: |
| if (backpage) |
| put_page(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) { |
| fscache_retrieval_complete(op, 1); |
| goto out; |
| } |
| io_error: |
| cachefiles_io_error_obj(object, "Page read error on backing file"); |
| fscache_retrieval_complete(op, 1); |
| ret = -ENOBUFS; |
| goto out; |
| |
| nomem_page: |
| put_page(newpage); |
| nomem_monitor: |
| fscache_put_retrieval(monitor->op); |
| kfree(monitor); |
| nomem: |
| fscache_retrieval_complete(op, 1); |
| _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 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) |
| goto enobufs; |
| |
| inode = d_backing_inode(object->backer); |
| 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 */ |
| 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; |
| |
| /* 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); |
| } else if (cachefiles_has_space(cache, 0, 1) == 0) { |
| /* there's space in the cache we can use */ |
| fscache_mark_page_cached(op, page); |
| fscache_retrieval_complete(op, 1); |
| ret = -ENODATA; |
| } else { |
| goto enobufs; |
| } |
| |
| _leave(" = %d", ret); |
| return ret; |
| |
| enobufs: |
| fscache_retrieval_complete(op, 1); |
| _leave(" = -ENOBUFS"); |
| return -ENOBUFS; |
| } |
| |
| /* |
| * 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 = d_backing_inode(object->backer)->i_mapping; |
| struct page *newpage = NULL, *netpage, *_n, *backpage = NULL; |
| int ret = 0; |
| |
| _enter(""); |
| |
| 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), cachefiles_gfp); |
| 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(cachefiles_gfp); |
| if (!newpage) |
| goto nomem; |
| } |
| |
| ret = add_to_page_cache_lru(newpage, bmapping, |
| netpage->index, |
| cachefiles_gfp); |
| 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 start it reading */ |
| installed_new_backing_page: |
| _debug("- new %p", newpage); |
| |
| backpage = newpage; |
| newpage = NULL; |
| |
| 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_lru(netpage, op->mapping, |
| netpage->index, cachefiles_gfp); |
| if (ret < 0) { |
| if (ret == -EEXIST) { |
| put_page(backpage); |
| backpage = NULL; |
| put_page(netpage); |
| netpage = NULL; |
| fscache_retrieval_complete(op, 1); |
| continue; |
| } |
| goto nomem; |
| } |
| |
| /* install a monitor */ |
| get_page(netpage); |
| monitor->netfs_page = netpage; |
| |
| get_page(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); |
| } |
| |
| put_page(backpage); |
| backpage = NULL; |
| |
| put_page(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_lru(netpage, op->mapping, |
| netpage->index, cachefiles_gfp); |
| if (ret < 0) { |
| if (ret == -EEXIST) { |
| put_page(backpage); |
| backpage = NULL; |
| put_page(netpage); |
| netpage = NULL; |
| fscache_retrieval_complete(op, 1); |
| continue; |
| } |
| goto nomem; |
| } |
| |
| copy_highpage(netpage, backpage); |
| |
| put_page(backpage); |
| backpage = NULL; |
| |
| fscache_mark_page_cached(op, netpage); |
| |
| /* the netpage is unlocked and marked up to date here */ |
| fscache_end_io(op, netpage, 0); |
| put_page(netpage); |
| netpage = NULL; |
| fscache_retrieval_complete(op, 1); |
| continue; |
| } |
| |
| netpage = NULL; |
| |
| _debug("out"); |
| |
| out: |
| /* tidy up */ |
| if (newpage) |
| put_page(newpage); |
| if (netpage) |
| put_page(netpage); |
| if (backpage) |
| put_page(backpage); |
| if (monitor) { |
| fscache_put_retrieval(op); |
| kfree(monitor); |
| } |
| |
| list_for_each_entry_safe(netpage, _n, list, lru) { |
| list_del(&netpage->lru); |
| put_page(netpage); |
| fscache_retrieval_complete(op, 1); |
| } |
| |
| _leave(" = %d", ret); |
| return ret; |
| |
| nomem: |
| _debug("nomem"); |
| ret = -ENOMEM; |
| goto record_page_complete; |
| |
| read_error: |
| _debug("read error %d", ret); |
| if (ret == -ENOMEM) |
| goto record_page_complete; |
| io_error: |
| cachefiles_io_error_obj(object, "Page read error on backing file"); |
| ret = -ENOBUFS; |
| record_page_complete: |
| fscache_retrieval_complete(op, 1); |
| 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) |
| goto all_enobufs; |
| |
| space = 1; |
| if (cachefiles_has_space(cache, 0, *nr_pages) < 0) |
| space = 0; |
| |
| inode = d_backing_inode(object->backer); |
| 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 */ |
| shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits; |
| |
| pagevec_init(&pagevec); |
| |
| 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); |
| fscache_retrieval_complete(op, 1); |
| ret = -ENODATA; |
| } else { |
| fscache_retrieval_complete(op, 1); |
| } |
| } |
| |
| 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; |
| |
| all_enobufs: |
| fscache_retrieval_complete(op, *nr_pages); |
| return -ENOBUFS; |
| } |
| |
| /* |
| * 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; |
| |
| fscache_retrieval_complete(op, 1); |
| _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); |
| |
| 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; |
| } |
| |
| fscache_retrieval_complete(op, *nr_pages); |
| _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; |
| struct file *file; |
| struct path path; |
| loff_t pos, eof; |
| size_t len; |
| void *data; |
| int ret = -ENOBUFS; |
| |
| 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(d_is_reg(object->backer)); |
| |
| cache = container_of(object->fscache.cache, |
| struct cachefiles_cache, cache); |
| |
| 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; |
| if (pos >= eof) |
| goto error; |
| |
| /* 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); |
| goto error_2; |
| } |
| |
| len = PAGE_SIZE; |
| if (eof & ~PAGE_MASK) { |
| if (eof - pos < PAGE_SIZE) { |
| _debug("cut short %llx to %llx", |
| pos, eof); |
| len = eof - pos; |
| ASSERTCMP(pos + len, ==, eof); |
| } |
| } |
| |
| data = kmap(page); |
| ret = __kernel_write(file, data, len, &pos); |
| kunmap(page); |
| fput(file); |
| if (ret != len) |
| goto error_eio; |
| |
| _leave(" = 0"); |
| return 0; |
| |
| error_eio: |
| ret = -EIO; |
| error_2: |
| if (ret == -EIO) |
| cachefiles_io_error_obj(object, |
| "Write page to backing file failed"); |
| error: |
| _leave(" = -ENOBUFS [%d]", ret); |
| return -ENOBUFS; |
| } |
| |
| /* |
| * 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) |
| __releases(&object->fscache.cookie->lock) |
| { |
| struct cachefiles_object *object; |
| |
| object = container_of(_object, struct cachefiles_object, fscache); |
| |
| _enter("%p,{%lu}", object, page->index); |
| |
| spin_unlock(&object->fscache.cookie->lock); |
| } |