| /* |
| * linux/mm/filemap.c |
| * |
| * Copyright (C) 1994-1999 Linus Torvalds |
| */ |
| |
| /* |
| * This file handles the generic file mmap semantics used by |
| * most "normal" filesystems (but you don't /have/ to use this: |
| * the NFS filesystem used to do this differently, for example) |
| */ |
| #include <linux/module.h> |
| #include <linux/compiler.h> |
| #include <linux/fs.h> |
| #include <linux/uaccess.h> |
| #include <linux/aio.h> |
| #include <linux/capability.h> |
| #include <linux/kernel_stat.h> |
| #include <linux/gfp.h> |
| #include <linux/mm.h> |
| #include <linux/swap.h> |
| #include <linux/mman.h> |
| #include <linux/pagemap.h> |
| #include <linux/file.h> |
| #include <linux/uio.h> |
| #include <linux/hash.h> |
| #include <linux/writeback.h> |
| #include <linux/backing-dev.h> |
| #include <linux/pagevec.h> |
| #include <linux/blkdev.h> |
| #include <linux/security.h> |
| #include <linux/syscalls.h> |
| #include <linux/cpuset.h> |
| #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */ |
| #include <linux/memcontrol.h> |
| #include <linux/mm_inline.h> /* for page_is_file_cache() */ |
| #include "internal.h" |
| |
| /* |
| * FIXME: remove all knowledge of the buffer layer from the core VM |
| */ |
| #include <linux/buffer_head.h> /* for try_to_free_buffers */ |
| |
| #include <asm/mman.h> |
| |
| /* |
| * Shared mappings implemented 30.11.1994. It's not fully working yet, |
| * though. |
| * |
| * Shared mappings now work. 15.8.1995 Bruno. |
| * |
| * finished 'unifying' the page and buffer cache and SMP-threaded the |
| * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> |
| * |
| * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> |
| */ |
| |
| /* |
| * Lock ordering: |
| * |
| * ->i_mmap_lock (truncate_pagecache) |
| * ->private_lock (__free_pte->__set_page_dirty_buffers) |
| * ->swap_lock (exclusive_swap_page, others) |
| * ->mapping->tree_lock |
| * |
| * ->i_mutex |
| * ->i_mmap_lock (truncate->unmap_mapping_range) |
| * |
| * ->mmap_sem |
| * ->i_mmap_lock |
| * ->page_table_lock or pte_lock (various, mainly in memory.c) |
| * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
| * |
| * ->mmap_sem |
| * ->lock_page (access_process_vm) |
| * |
| * ->i_mutex (generic_file_buffered_write) |
| * ->mmap_sem (fault_in_pages_readable->do_page_fault) |
| * |
| * ->i_mutex |
| * ->i_alloc_sem (various) |
| * |
| * ->inode_lock |
| * ->sb_lock (fs/fs-writeback.c) |
| * ->mapping->tree_lock (__sync_single_inode) |
| * |
| * ->i_mmap_lock |
| * ->anon_vma.lock (vma_adjust) |
| * |
| * ->anon_vma.lock |
| * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
| * |
| * ->page_table_lock or pte_lock |
| * ->swap_lock (try_to_unmap_one) |
| * ->private_lock (try_to_unmap_one) |
| * ->tree_lock (try_to_unmap_one) |
| * ->zone.lru_lock (follow_page->mark_page_accessed) |
| * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
| * ->private_lock (page_remove_rmap->set_page_dirty) |
| * ->tree_lock (page_remove_rmap->set_page_dirty) |
| * ->inode_lock (page_remove_rmap->set_page_dirty) |
| * ->inode_lock (zap_pte_range->set_page_dirty) |
| * ->private_lock (zap_pte_range->__set_page_dirty_buffers) |
| * |
| * (code doesn't rely on that order, so you could switch it around) |
| * ->tasklist_lock (memory_failure, collect_procs_ao) |
| * ->i_mmap_lock |
| */ |
| |
| /* |
| * Remove a page from the page cache and free it. Caller has to make |
| * sure the page is locked and that nobody else uses it - or that usage |
| * is safe. The caller must hold the mapping's tree_lock. |
| */ |
| void __remove_from_page_cache(struct page *page) |
| { |
| struct address_space *mapping = page->mapping; |
| |
| radix_tree_delete(&mapping->page_tree, page->index); |
| page->mapping = NULL; |
| mapping->nrpages--; |
| __dec_zone_page_state(page, NR_FILE_PAGES); |
| if (PageSwapBacked(page)) |
| __dec_zone_page_state(page, NR_SHMEM); |
| BUG_ON(page_mapped(page)); |
| |
| /* |
| * Some filesystems seem to re-dirty the page even after |
| * the VM has canceled the dirty bit (eg ext3 journaling). |
| * |
| * Fix it up by doing a final dirty accounting check after |
| * having removed the page entirely. |
| */ |
| if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { |
| dec_zone_page_state(page, NR_FILE_DIRTY); |
| dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); |
| } |
| } |
| |
| void remove_from_page_cache(struct page *page) |
| { |
| struct address_space *mapping = page->mapping; |
| void (*freepage)(struct page *); |
| |
| BUG_ON(!PageLocked(page)); |
| |
| freepage = mapping->a_ops->freepage; |
| spin_lock_irq(&mapping->tree_lock); |
| __remove_from_page_cache(page); |
| spin_unlock_irq(&mapping->tree_lock); |
| mem_cgroup_uncharge_cache_page(page); |
| |
| if (freepage) |
| freepage(page); |
| } |
| EXPORT_SYMBOL(remove_from_page_cache); |
| |
| static int sleep_on_page(void *word) |
| { |
| io_schedule(); |
| return 0; |
| } |
| |
| static int sleep_on_page_killable(void *word) |
| { |
| sleep_on_page(word); |
| return fatal_signal_pending(current) ? -EINTR : 0; |
| } |
| |
| /** |
| * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
| * @mapping: address space structure to write |
| * @start: offset in bytes where the range starts |
| * @end: offset in bytes where the range ends (inclusive) |
| * @sync_mode: enable synchronous operation |
| * |
| * Start writeback against all of a mapping's dirty pages that lie |
| * within the byte offsets <start, end> inclusive. |
| * |
| * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
| * opposed to a regular memory cleansing writeback. The difference between |
| * these two operations is that if a dirty page/buffer is encountered, it must |
| * be waited upon, and not just skipped over. |
| */ |
| int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
| loff_t end, int sync_mode) |
| { |
| int ret; |
| struct writeback_control wbc = { |
| .sync_mode = sync_mode, |
| .nr_to_write = LONG_MAX, |
| .range_start = start, |
| .range_end = end, |
| }; |
| |
| if (!mapping_cap_writeback_dirty(mapping)) |
| return 0; |
| |
| ret = do_writepages(mapping, &wbc); |
| return ret; |
| } |
| |
| static inline int __filemap_fdatawrite(struct address_space *mapping, |
| int sync_mode) |
| { |
| return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
| } |
| |
| int filemap_fdatawrite(struct address_space *mapping) |
| { |
| return __filemap_fdatawrite(mapping, WB_SYNC_ALL); |
| } |
| EXPORT_SYMBOL(filemap_fdatawrite); |
| |
| int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
| loff_t end) |
| { |
| return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); |
| } |
| EXPORT_SYMBOL(filemap_fdatawrite_range); |
| |
| /** |
| * filemap_flush - mostly a non-blocking flush |
| * @mapping: target address_space |
| * |
| * This is a mostly non-blocking flush. Not suitable for data-integrity |
| * purposes - I/O may not be started against all dirty pages. |
| */ |
| int filemap_flush(struct address_space *mapping) |
| { |
| return __filemap_fdatawrite(mapping, WB_SYNC_NONE); |
| } |
| EXPORT_SYMBOL(filemap_flush); |
| |
| /** |
| * filemap_fdatawait_range - wait for writeback to complete |
| * @mapping: address space structure to wait for |
| * @start_byte: offset in bytes where the range starts |
| * @end_byte: offset in bytes where the range ends (inclusive) |
| * |
| * Walk the list of under-writeback pages of the given address space |
| * in the given range and wait for all of them. |
| */ |
| int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, |
| loff_t end_byte) |
| { |
| pgoff_t index = start_byte >> PAGE_CACHE_SHIFT; |
| pgoff_t end = end_byte >> PAGE_CACHE_SHIFT; |
| struct pagevec pvec; |
| int nr_pages; |
| int ret = 0; |
| |
| if (end_byte < start_byte) |
| return 0; |
| |
| pagevec_init(&pvec, 0); |
| while ((index <= end) && |
| (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, |
| PAGECACHE_TAG_WRITEBACK, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { |
| unsigned i; |
| |
| for (i = 0; i < nr_pages; i++) { |
| struct page *page = pvec.pages[i]; |
| |
| /* until radix tree lookup accepts end_index */ |
| if (page->index > end) |
| continue; |
| |
| wait_on_page_writeback(page); |
| if (TestClearPageError(page)) |
| ret = -EIO; |
| } |
| pagevec_release(&pvec); |
| cond_resched(); |
| } |
| |
| /* Check for outstanding write errors */ |
| if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) |
| ret = -ENOSPC; |
| if (test_and_clear_bit(AS_EIO, &mapping->flags)) |
| ret = -EIO; |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(filemap_fdatawait_range); |
| |
| /** |
| * filemap_fdatawait - wait for all under-writeback pages to complete |
| * @mapping: address space structure to wait for |
| * |
| * Walk the list of under-writeback pages of the given address space |
| * and wait for all of them. |
| */ |
| int filemap_fdatawait(struct address_space *mapping) |
| { |
| loff_t i_size = i_size_read(mapping->host); |
| |
| if (i_size == 0) |
| return 0; |
| |
| return filemap_fdatawait_range(mapping, 0, i_size - 1); |
| } |
| EXPORT_SYMBOL(filemap_fdatawait); |
| |
| int filemap_write_and_wait(struct address_space *mapping) |
| { |
| int err = 0; |
| |
| if (mapping->nrpages) { |
| err = filemap_fdatawrite(mapping); |
| /* |
| * Even if the above returned error, the pages may be |
| * written partially (e.g. -ENOSPC), so we wait for it. |
| * But the -EIO is special case, it may indicate the worst |
| * thing (e.g. bug) happened, so we avoid waiting for it. |
| */ |
| if (err != -EIO) { |
| int err2 = filemap_fdatawait(mapping); |
| if (!err) |
| err = err2; |
| } |
| } |
| return err; |
| } |
| EXPORT_SYMBOL(filemap_write_and_wait); |
| |
| /** |
| * filemap_write_and_wait_range - write out & wait on a file range |
| * @mapping: the address_space for the pages |
| * @lstart: offset in bytes where the range starts |
| * @lend: offset in bytes where the range ends (inclusive) |
| * |
| * Write out and wait upon file offsets lstart->lend, inclusive. |
| * |
| * Note that `lend' is inclusive (describes the last byte to be written) so |
| * that this function can be used to write to the very end-of-file (end = -1). |
| */ |
| int filemap_write_and_wait_range(struct address_space *mapping, |
| loff_t lstart, loff_t lend) |
| { |
| int err = 0; |
| |
| if (mapping->nrpages) { |
| err = __filemap_fdatawrite_range(mapping, lstart, lend, |
| WB_SYNC_ALL); |
| /* See comment of filemap_write_and_wait() */ |
| if (err != -EIO) { |
| int err2 = filemap_fdatawait_range(mapping, |
| lstart, lend); |
| if (!err) |
| err = err2; |
| } |
| } |
| return err; |
| } |
| EXPORT_SYMBOL(filemap_write_and_wait_range); |
| |
| /** |
| * add_to_page_cache_locked - add a locked page to the pagecache |
| * @page: page to add |
| * @mapping: the page's address_space |
| * @offset: page index |
| * @gfp_mask: page allocation mode |
| * |
| * This function is used to add a page to the pagecache. It must be locked. |
| * This function does not add the page to the LRU. The caller must do that. |
| */ |
| int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
| pgoff_t offset, gfp_t gfp_mask) |
| { |
| int error; |
| |
| VM_BUG_ON(!PageLocked(page)); |
| |
| error = mem_cgroup_cache_charge(page, current->mm, |
| gfp_mask & GFP_RECLAIM_MASK); |
| if (error) |
| goto out; |
| |
| error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
| if (error == 0) { |
| page_cache_get(page); |
| page->mapping = mapping; |
| page->index = offset; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| error = radix_tree_insert(&mapping->page_tree, offset, page); |
| if (likely(!error)) { |
| mapping->nrpages++; |
| __inc_zone_page_state(page, NR_FILE_PAGES); |
| if (PageSwapBacked(page)) |
| __inc_zone_page_state(page, NR_SHMEM); |
| spin_unlock_irq(&mapping->tree_lock); |
| } else { |
| page->mapping = NULL; |
| spin_unlock_irq(&mapping->tree_lock); |
| mem_cgroup_uncharge_cache_page(page); |
| page_cache_release(page); |
| } |
| radix_tree_preload_end(); |
| } else |
| mem_cgroup_uncharge_cache_page(page); |
| out: |
| return error; |
| } |
| EXPORT_SYMBOL(add_to_page_cache_locked); |
| |
| int add_to_page_cache_lru(struct page *page, struct address_space *mapping, |
| pgoff_t offset, gfp_t gfp_mask) |
| { |
| int ret; |
| |
| /* |
| * Splice_read and readahead add shmem/tmpfs pages into the page cache |
| * before shmem_readpage has a chance to mark them as SwapBacked: they |
| * need to go on the anon lru below, and mem_cgroup_cache_charge |
| * (called in add_to_page_cache) needs to know where they're going too. |
| */ |
| if (mapping_cap_swap_backed(mapping)) |
| SetPageSwapBacked(page); |
| |
| ret = add_to_page_cache(page, mapping, offset, gfp_mask); |
| if (ret == 0) { |
| if (page_is_file_cache(page)) |
| lru_cache_add_file(page); |
| else |
| lru_cache_add_anon(page); |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
| |
| #ifdef CONFIG_NUMA |
| struct page *__page_cache_alloc(gfp_t gfp) |
| { |
| int n; |
| struct page *page; |
| |
| if (cpuset_do_page_mem_spread()) { |
| get_mems_allowed(); |
| n = cpuset_mem_spread_node(); |
| page = alloc_pages_exact_node(n, gfp, 0); |
| put_mems_allowed(); |
| return page; |
| } |
| return alloc_pages(gfp, 0); |
| } |
| EXPORT_SYMBOL(__page_cache_alloc); |
| #endif |
| |
| /* |
| * In order to wait for pages to become available there must be |
| * waitqueues associated with pages. By using a hash table of |
| * waitqueues where the bucket discipline is to maintain all |
| * waiters on the same queue and wake all when any of the pages |
| * become available, and for the woken contexts to check to be |
| * sure the appropriate page became available, this saves space |
| * at a cost of "thundering herd" phenomena during rare hash |
| * collisions. |
| */ |
| static wait_queue_head_t *page_waitqueue(struct page *page) |
| { |
| const struct zone *zone = page_zone(page); |
| |
| return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; |
| } |
| |
| static inline void wake_up_page(struct page *page, int bit) |
| { |
| __wake_up_bit(page_waitqueue(page), &page->flags, bit); |
| } |
| |
| void wait_on_page_bit(struct page *page, int bit_nr) |
| { |
| DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); |
| |
| if (test_bit(bit_nr, &page->flags)) |
| __wait_on_bit(page_waitqueue(page), &wait, sleep_on_page, |
| TASK_UNINTERRUPTIBLE); |
| } |
| EXPORT_SYMBOL(wait_on_page_bit); |
| |
| /** |
| * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue |
| * @page: Page defining the wait queue of interest |
| * @waiter: Waiter to add to the queue |
| * |
| * Add an arbitrary @waiter to the wait queue for the nominated @page. |
| */ |
| void add_page_wait_queue(struct page *page, wait_queue_t *waiter) |
| { |
| wait_queue_head_t *q = page_waitqueue(page); |
| unsigned long flags; |
| |
| spin_lock_irqsave(&q->lock, flags); |
| __add_wait_queue(q, waiter); |
| spin_unlock_irqrestore(&q->lock, flags); |
| } |
| EXPORT_SYMBOL_GPL(add_page_wait_queue); |
| |
| /** |
| * unlock_page - unlock a locked page |
| * @page: the page |
| * |
| * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). |
| * Also wakes sleepers in wait_on_page_writeback() because the wakeup |
| * mechananism between PageLocked pages and PageWriteback pages is shared. |
| * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. |
| * |
| * The mb is necessary to enforce ordering between the clear_bit and the read |
| * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). |
| */ |
| void unlock_page(struct page *page) |
| { |
| VM_BUG_ON(!PageLocked(page)); |
| clear_bit_unlock(PG_locked, &page->flags); |
| smp_mb__after_clear_bit(); |
| wake_up_page(page, PG_locked); |
| } |
| EXPORT_SYMBOL(unlock_page); |
| |
| /** |
| * end_page_writeback - end writeback against a page |
| * @page: the page |
| */ |
| void end_page_writeback(struct page *page) |
| { |
| if (TestClearPageReclaim(page)) |
| rotate_reclaimable_page(page); |
| |
| if (!test_clear_page_writeback(page)) |
| BUG(); |
| |
| smp_mb__after_clear_bit(); |
| wake_up_page(page, PG_writeback); |
| } |
| EXPORT_SYMBOL(end_page_writeback); |
| |
| /** |
| * __lock_page - get a lock on the page, assuming we need to sleep to get it |
| * @page: the page to lock |
| */ |
| void __lock_page(struct page *page) |
| { |
| DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
| |
| __wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page, |
| TASK_UNINTERRUPTIBLE); |
| } |
| EXPORT_SYMBOL(__lock_page); |
| |
| int __lock_page_killable(struct page *page) |
| { |
| DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
| |
| return __wait_on_bit_lock(page_waitqueue(page), &wait, |
| sleep_on_page_killable, TASK_KILLABLE); |
| } |
| EXPORT_SYMBOL_GPL(__lock_page_killable); |
| |
| int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
| unsigned int flags) |
| { |
| if (!(flags & FAULT_FLAG_ALLOW_RETRY)) { |
| __lock_page(page); |
| return 1; |
| } else { |
| up_read(&mm->mmap_sem); |
| wait_on_page_locked(page); |
| return 0; |
| } |
| } |
| |
| /** |
| * find_get_page - find and get a page reference |
| * @mapping: the address_space to search |
| * @offset: the page index |
| * |
| * Is there a pagecache struct page at the given (mapping, offset) tuple? |
| * If yes, increment its refcount and return it; if no, return NULL. |
| */ |
| struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
| { |
| void **pagep; |
| struct page *page; |
| |
| rcu_read_lock(); |
| repeat: |
| page = NULL; |
| pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); |
| if (pagep) { |
| page = radix_tree_deref_slot(pagep); |
| if (unlikely(!page)) |
| goto out; |
| if (radix_tree_deref_retry(page)) |
| goto repeat; |
| |
| if (!page_cache_get_speculative(page)) |
| goto repeat; |
| |
| /* |
| * Has the page moved? |
| * This is part of the lockless pagecache protocol. See |
| * include/linux/pagemap.h for details. |
| */ |
| if (unlikely(page != *pagep)) { |
| page_cache_release(page); |
| goto repeat; |
| } |
| } |
| out: |
| rcu_read_unlock(); |
| |
| return page; |
| } |
| EXPORT_SYMBOL(find_get_page); |
| |
| /** |
| * find_lock_page - locate, pin and lock a pagecache page |
| * @mapping: the address_space to search |
| * @offset: the page index |
| * |
| * Locates the desired pagecache page, locks it, increments its reference |
| * count and returns its address. |
| * |
| * Returns zero if the page was not present. find_lock_page() may sleep. |
| */ |
| struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
| { |
| struct page *page; |
| |
| repeat: |
| page = find_get_page(mapping, offset); |
| if (page) { |
| lock_page(page); |
| /* Has the page been truncated? */ |
| if (unlikely(page->mapping != mapping)) { |
| unlock_page(page); |
| page_cache_release(page); |
| goto repeat; |
| } |
| VM_BUG_ON(page->index != offset); |
| } |
| return page; |
| } |
| EXPORT_SYMBOL(find_lock_page); |
| |
| /** |
| * find_or_create_page - locate or add a pagecache page |
| * @mapping: the page's address_space |
| * @index: the page's index into the mapping |
| * @gfp_mask: page allocation mode |
| * |
| * Locates a page in the pagecache. If the page is not present, a new page |
| * is allocated using @gfp_mask and is added to the pagecache and to the VM's |
| * LRU list. The returned page is locked and has its reference count |
| * incremented. |
| * |
| * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic |
| * allocation! |
| * |
| * find_or_create_page() returns the desired page's address, or zero on |
| * memory exhaustion. |
| */ |
| struct page *find_or_create_page(struct address_space *mapping, |
| pgoff_t index, gfp_t gfp_mask) |
| { |
| struct page *page; |
| int err; |
| repeat: |
| page = find_lock_page(mapping, index); |
| if (!page) { |
| page = __page_cache_alloc(gfp_mask); |
| if (!page) |
| return NULL; |
| /* |
| * We want a regular kernel memory (not highmem or DMA etc) |
| * allocation for the radix tree nodes, but we need to honour |
| * the context-specific requirements the caller has asked for. |
| * GFP_RECLAIM_MASK collects those requirements. |
| */ |
| err = add_to_page_cache_lru(page, mapping, index, |
| (gfp_mask & GFP_RECLAIM_MASK)); |
| if (unlikely(err)) { |
| page_cache_release(page); |
| page = NULL; |
| if (err == -EEXIST) |
| goto repeat; |
| } |
| } |
| return page; |
| } |
| EXPORT_SYMBOL(find_or_create_page); |
| |
| /** |
| * find_get_pages - gang pagecache lookup |
| * @mapping: The address_space to search |
| * @start: The starting page index |
| * @nr_pages: The maximum number of pages |
| * @pages: Where the resulting pages are placed |
| * |
| * find_get_pages() will search for and return a group of up to |
| * @nr_pages pages in the mapping. The pages are placed at @pages. |
| * find_get_pages() takes a reference against the returned pages. |
| * |
| * The search returns a group of mapping-contiguous pages with ascending |
| * indexes. There may be holes in the indices due to not-present pages. |
| * |
| * find_get_pages() returns the number of pages which were found. |
| */ |
| unsigned find_get_pages(struct address_space *mapping, pgoff_t start, |
| unsigned int nr_pages, struct page **pages) |
| { |
| unsigned int i; |
| unsigned int ret; |
| unsigned int nr_found; |
| |
| rcu_read_lock(); |
| restart: |
| nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, |
| (void ***)pages, start, nr_pages); |
| ret = 0; |
| for (i = 0; i < nr_found; i++) { |
| struct page *page; |
| repeat: |
| page = radix_tree_deref_slot((void **)pages[i]); |
| if (unlikely(!page)) |
| continue; |
| if (radix_tree_deref_retry(page)) { |
| if (ret) |
| start = pages[ret-1]->index; |
| goto restart; |
| } |
| |
| if (!page_cache_get_speculative(page)) |
| goto repeat; |
| |
| /* Has the page moved? */ |
| if (unlikely(page != *((void **)pages[i]))) { |
| page_cache_release(page); |
| goto repeat; |
| } |
| |
| pages[ret] = page; |
| ret++; |
| } |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| /** |
| * find_get_pages_contig - gang contiguous pagecache lookup |
| * @mapping: The address_space to search |
| * @index: The starting page index |
| * @nr_pages: The maximum number of pages |
| * @pages: Where the resulting pages are placed |
| * |
| * find_get_pages_contig() works exactly like find_get_pages(), except |
| * that the returned number of pages are guaranteed to be contiguous. |
| * |
| * find_get_pages_contig() returns the number of pages which were found. |
| */ |
| unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, |
| unsigned int nr_pages, struct page **pages) |
| { |
| unsigned int i; |
| unsigned int ret; |
| unsigned int nr_found; |
| |
| rcu_read_lock(); |
| restart: |
| nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, |
| (void ***)pages, index, nr_pages); |
| ret = 0; |
| for (i = 0; i < nr_found; i++) { |
| struct page *page; |
| repeat: |
| page = radix_tree_deref_slot((void **)pages[i]); |
| if (unlikely(!page)) |
| continue; |
| if (radix_tree_deref_retry(page)) |
| goto restart; |
| |
| if (!page_cache_get_speculative(page)) |
| goto repeat; |
| |
| /* Has the page moved? */ |
| if (unlikely(page != *((void **)pages[i]))) { |
| page_cache_release(page); |
| goto repeat; |
| } |
| |
| /* |
| * must check mapping and index after taking the ref. |
| * otherwise we can get both false positives and false |
| * negatives, which is just confusing to the caller. |
| */ |
| if (page->mapping == NULL || page->index != index) { |
| page_cache_release(page); |
| break; |
| } |
| |
| pages[ret] = page; |
| ret++; |
| index++; |
| } |
| rcu_read_unlock(); |
| return ret; |
| } |
| EXPORT_SYMBOL(find_get_pages_contig); |
| |
| /** |
| * find_get_pages_tag - find and return pages that match @tag |
| * @mapping: the address_space to search |
| * @index: the starting page index |
| * @tag: the tag index |
| * @nr_pages: the maximum number of pages |
| * @pages: where the resulting pages are placed |
| * |
| * Like find_get_pages, except we only return pages which are tagged with |
| * @tag. We update @index to index the next page for the traversal. |
| */ |
| unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, |
| int tag, unsigned int nr_pages, struct page **pages) |
| { |
| unsigned int i; |
| unsigned int ret; |
| unsigned int nr_found; |
| |
| rcu_read_lock(); |
| restart: |
| nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, |
| (void ***)pages, *index, nr_pages, tag); |
| ret = 0; |
| for (i = 0; i < nr_found; i++) { |
| struct page *page; |
| repeat: |
| page = radix_tree_deref_slot((void **)pages[i]); |
| if (unlikely(!page)) |
| continue; |
| if (radix_tree_deref_retry(page)) |
| goto restart; |
| |
| if (!page_cache_get_speculative(page)) |
| goto repeat; |
| |
| /* Has the page moved? */ |
| if (unlikely(page != *((void **)pages[i]))) { |
| page_cache_release(page); |
| goto repeat; |
| } |
| |
| pages[ret] = page; |
| ret++; |
| } |
| rcu_read_unlock(); |
| |
| if (ret) |
| *index = pages[ret - 1]->index + 1; |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(find_get_pages_tag); |
| |
| /** |
| * grab_cache_page_nowait - returns locked page at given index in given cache |
| * @mapping: target address_space |
| * @index: the page index |
| * |
| * Same as grab_cache_page(), but do not wait if the page is unavailable. |
| * This is intended for speculative data generators, where the data can |
| * be regenerated if the page couldn't be grabbed. This routine should |
| * be safe to call while holding the lock for another page. |
| * |
| * Clear __GFP_FS when allocating the page to avoid recursion into the fs |
| * and deadlock against the caller's locked page. |
| */ |
| struct page * |
| grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
| { |
| struct page *page = find_get_page(mapping, index); |
| |
| if (page) { |
| if (trylock_page(page)) |
| return page; |
| page_cache_release(page); |
| return NULL; |
| } |
| page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
| if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
| page_cache_release(page); |
| page = NULL; |
| } |
| return page; |
| } |
| EXPORT_SYMBOL(grab_cache_page_nowait); |
| |
| /* |
| * CD/DVDs are error prone. When a medium error occurs, the driver may fail |
| * a _large_ part of the i/o request. Imagine the worst scenario: |
| * |
| * ---R__________________________________________B__________ |
| * ^ reading here ^ bad block(assume 4k) |
| * |
| * read(R) => miss => readahead(R...B) => media error => frustrating retries |
| * => failing the whole request => read(R) => read(R+1) => |
| * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => |
| * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => |
| * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... |
| * |
| * It is going insane. Fix it by quickly scaling down the readahead size. |
| */ |
| static void shrink_readahead_size_eio(struct file *filp, |
| struct file_ra_state *ra) |
| { |
| ra->ra_pages /= 4; |
| } |
| |
| /** |
| * do_generic_file_read - generic file read routine |
| * @filp: the file to read |
| * @ppos: current file position |
| * @desc: read_descriptor |
| * @actor: read method |
| * |
| * This is a generic file read routine, and uses the |
| * mapping->a_ops->readpage() function for the actual low-level stuff. |
| * |
| * This is really ugly. But the goto's actually try to clarify some |
| * of the logic when it comes to error handling etc. |
| */ |
| static void do_generic_file_read(struct file *filp, loff_t *ppos, |
| read_descriptor_t *desc, read_actor_t actor) |
| { |
| struct address_space *mapping = filp->f_mapping; |
| struct inode *inode = mapping->host; |
| struct file_ra_state *ra = &filp->f_ra; |
| pgoff_t index; |
| pgoff_t last_index; |
| pgoff_t prev_index; |
| unsigned long offset; /* offset into pagecache page */ |
| unsigned int prev_offset; |
| int error; |
| |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
| prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); |
| last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
| offset = *ppos & ~PAGE_CACHE_MASK; |
| |
| for (;;) { |
| struct page *page; |
| pgoff_t end_index; |
| loff_t isize; |
| unsigned long nr, ret; |
| |
| cond_resched(); |
| find_page: |
| page = find_get_page(mapping, index); |
| if (!page) { |
| page_cache_sync_readahead(mapping, |
| ra, filp, |
| index, last_index - index); |
| page = find_get_page(mapping, index); |
| if (unlikely(page == NULL)) |
| goto no_cached_page; |
| } |
| if (PageReadahead(page)) { |
| page_cache_async_readahead(mapping, |
| ra, filp, page, |
| index, last_index - index); |
| } |
| if (!PageUptodate(page)) { |
| if (inode->i_blkbits == PAGE_CACHE_SHIFT || |
| !mapping->a_ops->is_partially_uptodate) |
| goto page_not_up_to_date; |
| if (!trylock_page(page)) |
| goto page_not_up_to_date; |
| /* Did it get truncated before we got the lock? */ |
| if (!page->mapping) |
| goto page_not_up_to_date_locked; |
| if (!mapping->a_ops->is_partially_uptodate(page, |
| desc, offset)) |
| goto page_not_up_to_date_locked; |
| unlock_page(page); |
| } |
| page_ok: |
| /* |
| * i_size must be checked after we know the page is Uptodate. |
| * |
| * Checking i_size after the check allows us to calculate |
| * the correct value for "nr", which means the zero-filled |
| * part of the page is not copied back to userspace (unless |
| * another truncate extends the file - this is desired though). |
| */ |
| |
| isize = i_size_read(inode); |
| end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
| if (unlikely(!isize || index > end_index)) { |
| page_cache_release(page); |
| goto out; |
| } |
| |
| /* nr is the maximum number of bytes to copy from this page */ |
| nr = PAGE_CACHE_SIZE; |
| if (index == end_index) { |
| nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
| if (nr <= offset) { |
| page_cache_release(page); |
| goto out; |
| } |
| } |
| nr = nr - offset; |
| |
| /* If users can be writing to this page using arbitrary |
| * virtual addresses, take care about potential aliasing |
| * before reading the page on the kernel side. |
| */ |
| if (mapping_writably_mapped(mapping)) |
| flush_dcache_page(page); |
| |
| /* |
| * When a sequential read accesses a page several times, |
| * only mark it as accessed the first time. |
| */ |
| if (prev_index != index || offset != prev_offset) |
| mark_page_accessed(page); |
| prev_index = index; |
| |
| /* |
| * Ok, we have the page, and it's up-to-date, so |
| * now we can copy it to user space... |
| * |
| * The actor routine returns how many bytes were actually used.. |
| * NOTE! This may not be the same as how much of a user buffer |
| * we filled up (we may be padding etc), so we can only update |
| * "pos" here (the actor routine has to update the user buffer |
| * pointers and the remaining count). |
| */ |
| ret = actor(desc, page, offset, nr); |
| offset += ret; |
| index += offset >> PAGE_CACHE_SHIFT; |
| offset &= ~PAGE_CACHE_MASK; |
| prev_offset = offset; |
| |
| page_cache_release(page); |
| if (ret == nr && desc->count) |
| continue; |
| goto out; |
| |
| page_not_up_to_date: |
| /* Get exclusive access to the page ... */ |
| error = lock_page_killable(page); |
| if (unlikely(error)) |
| goto readpage_error; |
| |
| page_not_up_to_date_locked: |
| /* Did it get truncated before we got the lock? */ |
| if (!page->mapping) { |
| unlock_page(page); |
| page_cache_release(page); |
| continue; |
| } |
| |
| /* Did somebody else fill it already? */ |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto page_ok; |
| } |
| |
| readpage: |
| /* |
| * A previous I/O error may have been due to temporary |
| * failures, eg. multipath errors. |
| * PG_error will be set again if readpage fails. |
| */ |
| ClearPageError(page); |
| /* Start the actual read. The read will unlock the page. */ |
| error = mapping->a_ops->readpage(filp, page); |
| |
| if (unlikely(error)) { |
| if (error == AOP_TRUNCATED_PAGE) { |
| page_cache_release(page); |
| goto find_page; |
| } |
| goto readpage_error; |
| } |
| |
| if (!PageUptodate(page)) { |
| error = lock_page_killable(page); |
| if (unlikely(error)) |
| goto readpage_error; |
| if (!PageUptodate(page)) { |
| if (page->mapping == NULL) { |
| /* |
| * invalidate_mapping_pages got it |
| */ |
| unlock_page(page); |
| page_cache_release(page); |
| goto find_page; |
| } |
| unlock_page(page); |
| shrink_readahead_size_eio(filp, ra); |
| error = -EIO; |
| goto readpage_error; |
| } |
| unlock_page(page); |
| } |
| |
| goto page_ok; |
| |
| readpage_error: |
| /* UHHUH! A synchronous read error occurred. Report it */ |
| desc->error = error; |
| page_cache_release(page); |
| goto out; |
| |
| no_cached_page: |
| /* |
| * Ok, it wasn't cached, so we need to create a new |
| * page.. |
| */ |
| page = page_cache_alloc_cold(mapping); |
| if (!page) { |
| desc->error = -ENOMEM; |
| goto out; |
| } |
| error = add_to_page_cache_lru(page, mapping, |
| index, GFP_KERNEL); |
| if (error) { |
| page_cache_release(page); |
| if (error == -EEXIST) |
| goto find_page; |
| desc->error = error; |
| goto out; |
| } |
| goto readpage; |
| } |
| |
| out: |
| ra->prev_pos = prev_index; |
| ra->prev_pos <<= PAGE_CACHE_SHIFT; |
| ra->prev_pos |= prev_offset; |
| |
| *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
| file_accessed(filp); |
| } |
| |
| int file_read_actor(read_descriptor_t *desc, struct page *page, |
| unsigned long offset, unsigned long size) |
| { |
| char *kaddr; |
| unsigned long left, count = desc->count; |
| |
| if (size > count) |
| size = count; |
| |
| /* |
| * Faults on the destination of a read are common, so do it before |
| * taking the kmap. |
| */ |
| if (!fault_in_pages_writeable(desc->arg.buf, size)) { |
| kaddr = kmap_atomic(page, KM_USER0); |
| left = __copy_to_user_inatomic(desc->arg.buf, |
| kaddr + offset, size); |
| kunmap_atomic(kaddr, KM_USER0); |
| if (left == 0) |
| goto success; |
| } |
| |
| /* Do it the slow way */ |
| kaddr = kmap(page); |
| left = __copy_to_user(desc->arg.buf, kaddr + offset, size); |
| kunmap(page); |
| |
| if (left) { |
| size -= left; |
| desc->error = -EFAULT; |
| } |
| success: |
| desc->count = count - size; |
| desc->written += size; |
| desc->arg.buf += size; |
| return size; |
| } |
| |
| /* |
| * Performs necessary checks before doing a write |
| * @iov: io vector request |
| * @nr_segs: number of segments in the iovec |
| * @count: number of bytes to write |
| * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE |
| * |
| * Adjust number of segments and amount of bytes to write (nr_segs should be |
| * properly initialized first). Returns appropriate error code that caller |
| * should return or zero in case that write should be allowed. |
| */ |
| int generic_segment_checks(const struct iovec *iov, |
| unsigned long *nr_segs, size_t *count, int access_flags) |
| { |
| unsigned long seg; |
| size_t cnt = 0; |
| for (seg = 0; seg < *nr_segs; seg++) { |
| const struct iovec *iv = &iov[seg]; |
| |
| /* |
| * If any segment has a negative length, or the cumulative |
| * length ever wraps negative then return -EINVAL. |
| */ |
| cnt += iv->iov_len; |
| if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) |
| return -EINVAL; |
| if (access_ok(access_flags, iv->iov_base, iv->iov_len)) |
| continue; |
| if (seg == 0) |
| return -EFAULT; |
| *nr_segs = seg; |
| cnt -= iv->iov_len; /* This segment is no good */ |
| break; |
| } |
| *count = cnt; |
| return 0; |
| } |
| EXPORT_SYMBOL(generic_segment_checks); |
| |
| /** |
| * generic_file_aio_read - generic filesystem read routine |
| * @iocb: kernel I/O control block |
| * @iov: io vector request |
| * @nr_segs: number of segments in the iovec |
| * @pos: current file position |
| * |
| * This is the "read()" routine for all filesystems |
| * that can use the page cache directly. |
| */ |
| ssize_t |
| generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
| unsigned long nr_segs, loff_t pos) |
| { |
| struct file *filp = iocb->ki_filp; |
| ssize_t retval; |
| unsigned long seg = 0; |
| size_t count; |
| loff_t *ppos = &iocb->ki_pos; |
| |
| count = 0; |
| retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
| if (retval) |
| return retval; |
| |
| /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
| if (filp->f_flags & O_DIRECT) { |
| loff_t size; |
| struct address_space *mapping; |
| struct inode *inode; |
| |
| mapping = filp->f_mapping; |
| inode = mapping->host; |
| if (!count) |
| goto out; /* skip atime */ |
| size = i_size_read(inode); |
| if (pos < size) { |
| retval = filemap_write_and_wait_range(mapping, pos, |
| pos + iov_length(iov, nr_segs) - 1); |
| if (!retval) { |
| retval = mapping->a_ops->direct_IO(READ, iocb, |
| iov, pos, nr_segs); |
| } |
| if (retval > 0) { |
| *ppos = pos + retval; |
| count -= retval; |
| } |
| |
| /* |
| * Btrfs can have a short DIO read if we encounter |
| * compressed extents, so if there was an error, or if |
| * we've already read everything we wanted to, or if |
| * there was a short read because we hit EOF, go ahead |
| * and return. Otherwise fallthrough to buffered io for |
| * the rest of the read. |
| */ |
| if (retval < 0 || !count || *ppos >= size) { |
| file_accessed(filp); |
| goto out; |
| } |
| } |
| } |
| |
| count = retval; |
| for (seg = 0; seg < nr_segs; seg++) { |
| read_descriptor_t desc; |
| loff_t offset = 0; |
| |
| /* |
| * If we did a short DIO read we need to skip the section of the |
| * iov that we've already read data into. |
| */ |
| if (count) { |
| if (count > iov[seg].iov_len) { |
| count -= iov[seg].iov_len; |
| continue; |
| } |
| offset = count; |
| count = 0; |
| } |
| |
| desc.written = 0; |
| desc.arg.buf = iov[seg].iov_base + offset; |
| desc.count = iov[seg].iov_len - offset; |
| if (desc.count == 0) |
| continue; |
| desc.error = 0; |
| do_generic_file_read(filp, ppos, &desc, file_read_actor); |
| retval += desc.written; |
| if (desc.error) { |
| retval = retval ?: desc.error; |
| break; |
| } |
| if (desc.count > 0) |
| break; |
| } |
| out: |
| return retval; |
| } |
| EXPORT_SYMBOL(generic_file_aio_read); |
| |
| static ssize_t |
| do_readahead(struct address_space *mapping, struct file *filp, |
| pgoff_t index, unsigned long nr) |
| { |
| if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) |
| return -EINVAL; |
| |
| force_page_cache_readahead(mapping, filp, index, nr); |
| return 0; |
| } |
| |
| SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
| { |
| ssize_t ret; |
| struct file *file; |
| |
| ret = -EBADF; |
| file = fget(fd); |
| if (file) { |
| if (file->f_mode & FMODE_READ) { |
| struct address_space *mapping = file->f_mapping; |
| pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
| pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; |
| unsigned long len = end - start + 1; |
| ret = do_readahead(mapping, file, start, len); |
| } |
| fput(file); |
| } |
| return ret; |
| } |
| #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
| asmlinkage long SyS_readahead(long fd, loff_t offset, long count) |
| { |
| return SYSC_readahead((int) fd, offset, (size_t) count); |
| } |
| SYSCALL_ALIAS(sys_readahead, SyS_readahead); |
| #endif |
| |
| #ifdef CONFIG_MMU |
| /** |
| * page_cache_read - adds requested page to the page cache if not already there |
| * @file: file to read |
| * @offset: page index |
| * |
| * This adds the requested page to the page cache if it isn't already there, |
| * and schedules an I/O to read in its contents from disk. |
| */ |
| static int page_cache_read(struct file *file, pgoff_t offset) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct page *page; |
| int ret; |
| |
| do { |
| page = page_cache_alloc_cold(mapping); |
| if (!page) |
| return -ENOMEM; |
| |
| ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); |
| if (ret == 0) |
| ret = mapping->a_ops->readpage(file, page); |
| else if (ret == -EEXIST) |
| ret = 0; /* losing race to add is OK */ |
| |
| page_cache_release(page); |
| |
| } while (ret == AOP_TRUNCATED_PAGE); |
| |
| return ret; |
| } |
| |
| #define MMAP_LOTSAMISS (100) |
| |
| /* |
| * Synchronous readahead happens when we don't even find |
| * a page in the page cache at all. |
| */ |
| static void do_sync_mmap_readahead(struct vm_area_struct *vma, |
| struct file_ra_state *ra, |
| struct file *file, |
| pgoff_t offset) |
| { |
| unsigned long ra_pages; |
| struct address_space *mapping = file->f_mapping; |
| |
| /* If we don't want any read-ahead, don't bother */ |
| if (VM_RandomReadHint(vma)) |
| return; |
| |
| if (VM_SequentialReadHint(vma) || |
| offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) { |
| page_cache_sync_readahead(mapping, ra, file, offset, |
| ra->ra_pages); |
| return; |
| } |
| |
| if (ra->mmap_miss < INT_MAX) |
| ra->mmap_miss++; |
| |
| /* |
| * Do we miss much more than hit in this file? If so, |
| * stop bothering with read-ahead. It will only hurt. |
| */ |
| if (ra->mmap_miss > MMAP_LOTSAMISS) |
| return; |
| |
| /* |
| * mmap read-around |
| */ |
| ra_pages = max_sane_readahead(ra->ra_pages); |
| if (ra_pages) { |
| ra->start = max_t(long, 0, offset - ra_pages/2); |
| ra->size = ra_pages; |
| ra->async_size = 0; |
| ra_submit(ra, mapping, file); |
| } |
| } |
| |
| /* |
| * Asynchronous readahead happens when we find the page and PG_readahead, |
| * so we want to possibly extend the readahead further.. |
| */ |
| static void do_async_mmap_readahead(struct vm_area_struct *vma, |
| struct file_ra_state *ra, |
| struct file *file, |
| struct page *page, |
| pgoff_t offset) |
| { |
| struct address_space *mapping = file->f_mapping; |
| |
| /* If we don't want any read-ahead, don't bother */ |
| if (VM_RandomReadHint(vma)) |
| return; |
| if (ra->mmap_miss > 0) |
| ra->mmap_miss--; |
| if (PageReadahead(page)) |
| page_cache_async_readahead(mapping, ra, file, |
| page, offset, ra->ra_pages); |
| } |
| |
| /** |
| * filemap_fault - read in file data for page fault handling |
| * @vma: vma in which the fault was taken |
| * @vmf: struct vm_fault containing details of the fault |
| * |
| * filemap_fault() is invoked via the vma operations vector for a |
| * mapped memory region to read in file data during a page fault. |
| * |
| * The goto's are kind of ugly, but this streamlines the normal case of having |
| * it in the page cache, and handles the special cases reasonably without |
| * having a lot of duplicated code. |
| */ |
| int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
| { |
| int error; |
| struct file *file = vma->vm_file; |
| struct address_space *mapping = file->f_mapping; |
| struct file_ra_state *ra = &file->f_ra; |
| struct inode *inode = mapping->host; |
| pgoff_t offset = vmf->pgoff; |
| struct page *page; |
| pgoff_t size; |
| int ret = 0; |
| |
| size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| if (offset >= size) |
| return VM_FAULT_SIGBUS; |
| |
| /* |
| * Do we have something in the page cache already? |
| */ |
| page = find_get_page(mapping, offset); |
| if (likely(page)) { |
| /* |
| * We found the page, so try async readahead before |
| * waiting for the lock. |
| */ |
| do_async_mmap_readahead(vma, ra, file, page, offset); |
| } else { |
| /* No page in the page cache at all */ |
| do_sync_mmap_readahead(vma, ra, file, offset); |
| count_vm_event(PGMAJFAULT); |
| ret = VM_FAULT_MAJOR; |
| retry_find: |
| page = find_get_page(mapping, offset); |
| if (!page) |
| goto no_cached_page; |
| } |
| |
| if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) { |
| page_cache_release(page); |
| return ret | VM_FAULT_RETRY; |
| } |
| |
| /* Did it get truncated? */ |
| if (unlikely(page->mapping != mapping)) { |
| unlock_page(page); |
| put_page(page); |
| goto retry_find; |
| } |
| VM_BUG_ON(page->index != offset); |
| |
| /* |
| * We have a locked page in the page cache, now we need to check |
| * that it's up-to-date. If not, it is going to be due to an error. |
| */ |
| if (unlikely(!PageUptodate(page))) |
| goto page_not_uptodate; |
| |
| /* |
| * Found the page and have a reference on it. |
| * We must recheck i_size under page lock. |
| */ |
| size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| if (unlikely(offset >= size)) { |
| unlock_page(page); |
| page_cache_release(page); |
| return VM_FAULT_SIGBUS; |
| } |
| |
| ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT; |
| vmf->page = page; |
| return ret | VM_FAULT_LOCKED; |
| |
| no_cached_page: |
| /* |
| * We're only likely to ever get here if MADV_RANDOM is in |
| * effect. |
| */ |
| error = page_cache_read(file, offset); |
| |
| /* |
| * The page we want has now been added to the page cache. |
| * In the unlikely event that someone removed it in the |
| * meantime, we'll just come back here and read it again. |
| */ |
| if (error >= 0) |
| goto retry_find; |
| |
| /* |
| * An error return from page_cache_read can result if the |
| * system is low on memory, or a problem occurs while trying |
| * to schedule I/O. |
| */ |
| if (error == -ENOMEM) |
| return VM_FAULT_OOM; |
| return VM_FAULT_SIGBUS; |
| |
| page_not_uptodate: |
| /* |
| * Umm, take care of errors if the page isn't up-to-date. |
| * Try to re-read it _once_. We do this synchronously, |
| * because there really aren't any performance issues here |
| * and we need to check for errors. |
| */ |
| ClearPageError(page); |
| error = mapping->a_ops->readpage(file, page); |
| if (!error) { |
| wait_on_page_locked(page); |
| if (!PageUptodate(page)) |
| error = -EIO; |
| } |
| page_cache_release(page); |
| |
| if (!error || error == AOP_TRUNCATED_PAGE) |
| goto retry_find; |
| |
| /* Things didn't work out. Return zero to tell the mm layer so. */ |
| shrink_readahead_size_eio(file, ra); |
| return VM_FAULT_SIGBUS; |
| } |
| EXPORT_SYMBOL(filemap_fault); |
| |
| const struct vm_operations_struct generic_file_vm_ops = { |
| .fault = filemap_fault, |
| }; |
| |
| /* This is used for a general mmap of a disk file */ |
| |
| int generic_file_mmap(struct file * file, struct vm_area_struct * vma) |
| { |
| struct address_space *mapping = file->f_mapping; |
| |
| if (!mapping->a_ops->readpage) |
| return -ENOEXEC; |
| file_accessed(file); |
| vma->vm_ops = &generic_file_vm_ops; |
| vma->vm_flags |= VM_CAN_NONLINEAR; |
| return 0; |
| } |
| |
| /* |
| * This is for filesystems which do not implement ->writepage. |
| */ |
| int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) |
| return -EINVAL; |
| return generic_file_mmap(file, vma); |
| } |
| #else |
| int generic_file_mmap(struct file * file, struct vm_area_struct * vma) |
| { |
| return -ENOSYS; |
| } |
| int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) |
| { |
| return -ENOSYS; |
| } |
| #endif /* CONFIG_MMU */ |
| |
| EXPORT_SYMBOL(generic_file_mmap); |
| EXPORT_SYMBOL(generic_file_readonly_mmap); |
| |
| static struct page *__read_cache_page(struct address_space *mapping, |
| pgoff_t index, |
| int (*filler)(void *,struct page*), |
| void *data, |
| gfp_t gfp) |
| { |
| struct page *page; |
| int err; |
| repeat: |
| page = find_get_page(mapping, index); |
| if (!page) { |
| page = __page_cache_alloc(gfp | __GFP_COLD); |
| if (!page) |
| return ERR_PTR(-ENOMEM); |
| err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); |
| if (unlikely(err)) { |
| page_cache_release(page); |
| if (err == -EEXIST) |
| goto repeat; |
| /* Presumably ENOMEM for radix tree node */ |
| return ERR_PTR(err); |
| } |
| err = filler(data, page); |
| if (err < 0) { |
| page_cache_release(page); |
| page = ERR_PTR(err); |
| } |
| } |
| return page; |
| } |
| |
| static struct page *do_read_cache_page(struct address_space *mapping, |
| pgoff_t index, |
| int (*filler)(void *,struct page*), |
| void *data, |
| gfp_t gfp) |
| |
| { |
| struct page *page; |
| int err; |
| |
| retry: |
| page = __read_cache_page(mapping, index, filler, data, gfp); |
| if (IS_ERR(page)) |
| return page; |
| if (PageUptodate(page)) |
| goto out; |
| |
| lock_page(page); |
| if (!page->mapping) { |
| unlock_page(page); |
| page_cache_release(page); |
| goto retry; |
| } |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto out; |
| } |
| err = filler(data, page); |
| if (err < 0) { |
| page_cache_release(page); |
| return ERR_PTR(err); |
| } |
| out: |
| mark_page_accessed(page); |
| return page; |
| } |
| |
| /** |
| * read_cache_page_async - read into page cache, fill it if needed |
| * @mapping: the page's address_space |
| * @index: the page index |
| * @filler: function to perform the read |
| * @data: destination for read data |
| * |
| * Same as read_cache_page, but don't wait for page to become unlocked |
| * after submitting it to the filler. |
| * |
| * Read into the page cache. If a page already exists, and PageUptodate() is |
| * not set, try to fill the page but don't wait for it to become unlocked. |
| * |
| * If the page does not get brought uptodate, return -EIO. |
| */ |
| struct page *read_cache_page_async(struct address_space *mapping, |
| pgoff_t index, |
| int (*filler)(void *,struct page*), |
| void *data) |
| { |
| return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping)); |
| } |
| EXPORT_SYMBOL(read_cache_page_async); |
| |
| static struct page *wait_on_page_read(struct page *page) |
| { |
| if (!IS_ERR(page)) { |
| wait_on_page_locked(page); |
| if (!PageUptodate(page)) { |
| page_cache_release(page); |
| page = ERR_PTR(-EIO); |
| } |
| } |
| return page; |
| } |
| |
| /** |
| * read_cache_page_gfp - read into page cache, using specified page allocation flags. |
| * @mapping: the page's address_space |
| * @index: the page index |
| * @gfp: the page allocator flags to use if allocating |
| * |
| * This is the same as "read_mapping_page(mapping, index, NULL)", but with |
| * any new page allocations done using the specified allocation flags. Note |
| * that the Radix tree operations will still use GFP_KERNEL, so you can't |
| * expect to do this atomically or anything like that - but you can pass in |
| * other page requirements. |
| * |
| * If the page does not get brought uptodate, return -EIO. |
| */ |
| struct page *read_cache_page_gfp(struct address_space *mapping, |
| pgoff_t index, |
| gfp_t gfp) |
| { |
| filler_t *filler = (filler_t *)mapping->a_ops->readpage; |
| |
| return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp)); |
| } |
| EXPORT_SYMBOL(read_cache_page_gfp); |
| |
| /** |
| * read_cache_page - read into page cache, fill it if needed |
| * @mapping: the page's address_space |
| * @index: the page index |
| * @filler: function to perform the read |
| * @data: destination for read data |
| * |
| * Read into the page cache. If a page already exists, and PageUptodate() is |
| * not set, try to fill the page then wait for it to become unlocked. |
| * |
| * If the page does not get brought uptodate, return -EIO. |
| */ |
| struct page *read_cache_page(struct address_space *mapping, |
| pgoff_t index, |
| int (*filler)(void *,struct page*), |
| void *data) |
| { |
| return wait_on_page_read(read_cache_page_async(mapping, index, filler, data)); |
| } |
| EXPORT_SYMBOL(read_cache_page); |
| |
| /* |
| * The logic we want is |
| * |
| * if suid or (sgid and xgrp) |
| * remove privs |
| */ |
| int should_remove_suid(struct dentry *dentry) |
| { |
| mode_t mode = dentry->d_inode->i_mode; |
| int kill = 0; |
| |
| /* suid always must be killed */ |
| if (unlikely(mode & S_ISUID)) |
| kill = ATTR_KILL_SUID; |
| |
| /* |
| * sgid without any exec bits is just a mandatory locking mark; leave |
| * it alone. If some exec bits are set, it's a real sgid; kill it. |
| */ |
| if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) |
| kill |= ATTR_KILL_SGID; |
| |
| if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
| return kill; |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(should_remove_suid); |
| |
| static int __remove_suid(struct dentry *dentry, int kill) |
| { |
| struct iattr newattrs; |
| |
| newattrs.ia_valid = ATTR_FORCE | kill; |
| return notify_change(dentry, &newattrs); |
| } |
| |
| int file_remove_suid(struct file *file) |
| { |
| struct dentry *dentry = file->f_path.dentry; |
| int killsuid = should_remove_suid(dentry); |
| int killpriv = security_inode_need_killpriv(dentry); |
| int error = 0; |
| |
| if (killpriv < 0) |
| return killpriv; |
| if (killpriv) |
| error = security_inode_killpriv(dentry); |
| if (!error && killsuid) |
| error = __remove_suid(dentry, killsuid); |
| |
| return error; |
| } |
| EXPORT_SYMBOL(file_remove_suid); |
| |
| static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
| const struct iovec *iov, size_t base, size_t bytes) |
| { |
| size_t copied = 0, left = 0; |
| |
| while (bytes) { |
| char __user *buf = iov->iov_base + base; |
| int copy = min(bytes, iov->iov_len - base); |
| |
| base = 0; |
| left = __copy_from_user_inatomic(vaddr, buf, copy); |
| copied += copy; |
| bytes -= copy; |
| vaddr += copy; |
| iov++; |
| |
| if (unlikely(left)) |
| break; |
| } |
| return copied - left; |
| } |
| |
| /* |
| * Copy as much as we can into the page and return the number of bytes which |
| * were successfully copied. If a fault is encountered then return the number of |
| * bytes which were copied. |
| */ |
| size_t iov_iter_copy_from_user_atomic(struct page *page, |
| struct iov_iter *i, unsigned long offset, size_t bytes) |
| { |
| char *kaddr; |
| size_t copied; |
| |
| BUG_ON(!in_atomic()); |
| kaddr = kmap_atomic(page, KM_USER0); |
| if (likely(i->nr_segs == 1)) { |
| int left; |
| char __user *buf = i->iov->iov_base + i->iov_offset; |
| left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
| copied = bytes - left; |
| } else { |
| copied = __iovec_copy_from_user_inatomic(kaddr + offset, |
| i->iov, i->iov_offset, bytes); |
| } |
| kunmap_atomic(kaddr, KM_USER0); |
| |
| return copied; |
| } |
| EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
| |
| /* |
| * This has the same sideeffects and return value as |
| * iov_iter_copy_from_user_atomic(). |
| * The difference is that it attempts to resolve faults. |
| * Page must not be locked. |
| */ |
| size_t iov_iter_copy_from_user(struct page *page, |
| struct iov_iter *i, unsigned long offset, size_t bytes) |
| { |
| char *kaddr; |
| size_t copied; |
| |
| kaddr = kmap(page); |
| if (likely(i->nr_segs == 1)) { |
| int left; |
| char __user *buf = i->iov->iov_base + i->iov_offset; |
| left = __copy_from_user(kaddr + offset, buf, bytes); |
| copied = bytes - left; |
| } else { |
| copied = __iovec_copy_from_user_inatomic(kaddr + offset, |
| i->iov, i->iov_offset, bytes); |
| } |
| kunmap(page); |
| return copied; |
| } |
| EXPORT_SYMBOL(iov_iter_copy_from_user); |
| |
| void iov_iter_advance(struct iov_iter *i, size_t bytes) |
| { |
| BUG_ON(i->count < bytes); |
| |
| if (likely(i->nr_segs == 1)) { |
| i->iov_offset += bytes; |
| i->count -= bytes; |
| } else { |
| const struct iovec *iov = i->iov; |
| size_t base = i->iov_offset; |
| |
| /* |
| * The !iov->iov_len check ensures we skip over unlikely |
| * zero-length segments (without overruning the iovec). |
| */ |
| while (bytes || unlikely(i->count && !iov->iov_len)) { |
| int copy; |
| |
| copy = min(bytes, iov->iov_len - base); |
| BUG_ON(!i->count || i->count < copy); |
| i->count -= copy; |
| bytes -= copy; |
| base += copy; |
| if (iov->iov_len == base) { |
| iov++; |
| base = 0; |
| } |
| } |
| i->iov = iov; |
| i->iov_offset = base; |
| } |
| } |
| EXPORT_SYMBOL(iov_iter_advance); |
| |
| /* |
| * Fault in the first iovec of the given iov_iter, to a maximum length |
| * of bytes. Returns 0 on success, or non-zero if the memory could not be |
| * accessed (ie. because it is an invalid address). |
| * |
| * writev-intensive code may want this to prefault several iovecs -- that |
| * would be possible (callers must not rely on the fact that _only_ the |
| * first iovec will be faulted with the current implementation). |
| */ |
| int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) |
| { |
| char __user *buf = i->iov->iov_base + i->iov_offset; |
| bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
| return fault_in_pages_readable(buf, bytes); |
| } |
| EXPORT_SYMBOL(iov_iter_fault_in_readable); |
| |
| /* |
| * Return the count of just the current iov_iter segment. |
| */ |
| size_t iov_iter_single_seg_count(struct iov_iter *i) |
| { |
| const struct iovec *iov = i->iov; |
| if (i->nr_segs == 1) |
| return i->count; |
| else |
| return min(i->count, iov->iov_len - i->iov_offset); |
| } |
| EXPORT_SYMBOL(iov_iter_single_seg_count); |
| |
| /* |
| * Performs necessary checks before doing a write |
| * |
| * Can adjust writing position or amount of bytes to write. |
| * Returns appropriate error code that caller should return or |
| * zero in case that write should be allowed. |
| */ |
| inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) |
| { |
| struct inode *inode = file->f_mapping->host; |
| unsigned long limit = rlimit(RLIMIT_FSIZE); |
| |
| if (unlikely(*pos < 0)) |
| return -EINVAL; |
| |
| if (!isblk) { |
| /* FIXME: this is for backwards compatibility with 2.4 */ |
| if (file->f_flags & O_APPEND) |
| *pos = i_size_read(inode); |
| |
| if (limit != RLIM_INFINITY) { |
| if (*pos >= limit) { |
| send_sig(SIGXFSZ, current, 0); |
| return -EFBIG; |
| } |
| if (*count > limit - (typeof(limit))*pos) { |
| *count = limit - (typeof(limit))*pos; |
| } |
| } |
| } |
| |
| /* |
| * LFS rule |
| */ |
| if (unlikely(*pos + *count > MAX_NON_LFS && |
| !(file->f_flags & O_LARGEFILE))) { |
| if (*pos >= MAX_NON_LFS) { |
| return -EFBIG; |
| } |
| if (*count > MAX_NON_LFS - (unsigned long)*pos) { |
| *count = MAX_NON_LFS - (unsigned long)*pos; |
| } |
| } |
| |
| /* |
| * Are we about to exceed the fs block limit ? |
| * |
| * If we have written data it becomes a short write. If we have |
| * exceeded without writing data we send a signal and return EFBIG. |
| * Linus frestrict idea will clean these up nicely.. |
| */ |
| if (likely(!isblk)) { |
| if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { |
| if (*count || *pos > inode->i_sb->s_maxbytes) { |
| return -EFBIG; |
| } |
| /* zero-length writes at ->s_maxbytes are OK */ |
| } |
| |
| if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) |
| *count = inode->i_sb->s_maxbytes - *pos; |
| } else { |
| #ifdef CONFIG_BLOCK |
| loff_t isize; |
| if (bdev_read_only(I_BDEV(inode))) |
| return -EPERM; |
| isize = i_size_read(inode); |
| if (*pos >= isize) { |
| if (*count || *pos > isize) |
| return -ENOSPC; |
| } |
| |
| if (*pos + *count > isize) |
| *count = isize - *pos; |
| #else |
| return -EPERM; |
| #endif |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL(generic_write_checks); |
| |
| int pagecache_write_begin(struct file *file, struct address_space *mapping, |
| loff_t pos, unsigned len, unsigned flags, |
| struct page **pagep, void **fsdata) |
| { |
| const struct address_space_operations *aops = mapping->a_ops; |
| |
| return aops->write_begin(file, mapping, pos, len, flags, |
| pagep, fsdata); |
| } |
| EXPORT_SYMBOL(pagecache_write_begin); |
| |
| int pagecache_write_end(struct file *file, struct address_space *mapping, |
| loff_t pos, unsigned len, unsigned copied, |
| struct page *page, void *fsdata) |
| { |
| const struct address_space_operations *aops = mapping->a_ops; |
| |
| mark_page_accessed(page); |
| return aops->write_end(file, mapping, pos, len, copied, page, fsdata); |
| } |
| EXPORT_SYMBOL(pagecache_write_end); |
| |
| ssize_t |
| generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, |
| unsigned long *nr_segs, loff_t pos, loff_t *ppos, |
| size_t count, size_t ocount) |
| { |
| struct file *file = iocb->ki_filp; |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| ssize_t written; |
| size_t write_len; |
| pgoff_t end; |
| |
| if (count != ocount) |
| *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); |
| |
| write_len = iov_length(iov, *nr_segs); |
| end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; |
| |
| written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
| if (written) |
| goto out; |
| |
| /* |
| * After a write we want buffered reads to be sure to go to disk to get |
| * the new data. We invalidate clean cached page from the region we're |
| * about to write. We do this *before* the write so that we can return |
| * without clobbering -EIOCBQUEUED from ->direct_IO(). |
| */ |
| if (mapping->nrpages) { |
| written = invalidate_inode_pages2_range(mapping, |
| pos >> PAGE_CACHE_SHIFT, end); |
| /* |
| * If a page can not be invalidated, return 0 to fall back |
| * to buffered write. |
| */ |
| if (written) { |
| if (written == -EBUSY) |
| return 0; |
| goto out; |
| } |
| } |
| |
| written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); |
| |
| /* |
| * Finally, try again to invalidate clean pages which might have been |
| * cached by non-direct readahead, or faulted in by get_user_pages() |
| * if the source of the write was an mmap'ed region of the file |
| * we're writing. Either one is a pretty crazy thing to do, |
| * so we don't support it 100%. If this invalidation |
| * fails, tough, the write still worked... |
| */ |
| if (mapping->nrpages) { |
| invalidate_inode_pages2_range(mapping, |
| pos >> PAGE_CACHE_SHIFT, end); |
| } |
| |
| if (written > 0) { |
| pos += written; |
| if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { |
| i_size_write(inode, pos); |
| mark_inode_dirty(inode); |
| } |
| *ppos = pos; |
| } |
| out: |
| return written; |
| } |
| EXPORT_SYMBOL(generic_file_direct_write); |
| |
| /* |
| * Find or create a page at the given pagecache position. Return the locked |
| * page. This function is specifically for buffered writes. |
| */ |
| struct page *grab_cache_page_write_begin(struct address_space *mapping, |
| pgoff_t index, unsigned flags) |
| { |
| int status; |
| struct page *page; |
| gfp_t gfp_notmask = 0; |
| if (flags & AOP_FLAG_NOFS) |
| gfp_notmask = __GFP_FS; |
| repeat: |
| page = find_lock_page(mapping, index); |
| if (page) |
| return page; |
| |
| page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
| if (!page) |
| return NULL; |
| status = add_to_page_cache_lru(page, mapping, index, |
| GFP_KERNEL & ~gfp_notmask); |
| if (unlikely(status)) { |
| page_cache_release(page); |
| if (status == -EEXIST) |
| goto repeat; |
| return NULL; |
| } |
| return page; |
| } |
| EXPORT_SYMBOL(grab_cache_page_write_begin); |
| |
| static ssize_t generic_perform_write(struct file *file, |
| struct iov_iter *i, loff_t pos) |
| { |
| struct address_space *mapping = file->f_mapping; |
| const struct address_space_operations *a_ops = mapping->a_ops; |
| long status = 0; |
| ssize_t written = 0; |
| unsigned int flags = 0; |
| |
| /* |
| * Copies from kernel address space cannot fail (NFSD is a big user). |
| */ |
| if (segment_eq(get_fs(), KERNEL_DS)) |
| flags |= AOP_FLAG_UNINTERRUPTIBLE; |
| |
| do { |
| struct page *page; |
| unsigned long offset; /* Offset into pagecache page */ |
| unsigned long bytes; /* Bytes to write to page */ |
| size_t copied; /* Bytes copied from user */ |
| void *fsdata; |
| |
| offset = (pos & (PAGE_CACHE_SIZE - 1)); |
| bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
| iov_iter_count(i)); |
| |
| again: |
| |
| /* |
| * Bring in the user page that we will copy from _first_. |
| * Otherwise there's a nasty deadlock on copying from the |
| * same page as we're writing to, without it being marked |
| * up-to-date. |
| * |
| * Not only is this an optimisation, but it is also required |
| * to check that the address is actually valid, when atomic |
| * usercopies are used, below. |
| */ |
| if (unlikely(iov_iter_fault_in_readable(i, bytes))) { |
| status = -EFAULT; |
| break; |
| } |
| |
| status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
| &page, &fsdata); |
| if (unlikely(status)) |
| break; |
| |
| if (mapping_writably_mapped(mapping)) |
| flush_dcache_page(page); |
| |
| pagefault_disable(); |
| copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); |
| pagefault_enable(); |
| flush_dcache_page(page); |
| |
| mark_page_accessed(page); |
| status = a_ops->write_end(file, mapping, pos, bytes, copied, |
| page, fsdata); |
| if (unlikely(status < 0)) |
| break; |
| copied = status; |
| |
| cond_resched(); |
| |
| iov_iter_advance(i, copied); |
| if (unlikely(copied == 0)) { |
| /* |
| * If we were unable to copy any data at all, we must |
| * fall back to a single segment length write. |
| * |
| * If we didn't fallback here, we could livelock |
| * because not all segments in the iov can be copied at |
| * once without a pagefault. |
| */ |
| bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
| iov_iter_single_seg_count(i)); |
| goto again; |
| } |
| pos += copied; |
| written += copied; |
| |
| balance_dirty_pages_ratelimited(mapping); |
| |
| } while (iov_iter_count(i)); |
| |
| return written ? written : status; |
| } |
| |
| ssize_t |
| generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, |
| unsigned long nr_segs, loff_t pos, loff_t *ppos, |
| size_t count, ssize_t written) |
| { |
| struct file *file = iocb->ki_filp; |
| ssize_t status; |
| struct iov_iter i; |
| |
| iov_iter_init(&i, iov, nr_segs, count, written); |
| status = generic_perform_write(file, &i, pos); |
| |
| if (likely(status >= 0)) { |
| written += status; |
| *ppos = pos + status; |
| } |
| |
| return written ? written : status; |
| } |
| EXPORT_SYMBOL(generic_file_buffered_write); |
| |
| /** |
| * __generic_file_aio_write - write data to a file |
| * @iocb: IO state structure (file, offset, etc.) |
| * @iov: vector with data to write |
| * @nr_segs: number of segments in the vector |
| * @ppos: position where to write |
| * |
| * This function does all the work needed for actually writing data to a |
| * file. It does all basic checks, removes SUID from the file, updates |
| * modification times and calls proper subroutines depending on whether we |
| * do direct IO or a standard buffered write. |
| * |
| * It expects i_mutex to be grabbed unless we work on a block device or similar |
| * object which does not need locking at all. |
| * |
| * This function does *not* take care of syncing data in case of O_SYNC write. |
| * A caller has to handle it. This is mainly due to the fact that we want to |
| * avoid syncing under i_mutex. |
| */ |
| ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct file *file = iocb->ki_filp; |
| struct address_space * mapping = file->f_mapping; |
| size_t ocount; /* original count */ |
| size_t count; /* after file limit checks */ |
| struct inode *inode = mapping->host; |
| loff_t pos; |
| ssize_t written; |
| ssize_t err; |
| |
| ocount = 0; |
| err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
| if (err) |
| return err; |
| |
| count = ocount; |
| pos = *ppos; |
| |
| vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); |
| |
| /* We can write back this queue in page reclaim */ |
| current->backing_dev_info = mapping->backing_dev_info; |
| written = 0; |
| |
| err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); |
| if (err) |
| goto out; |
| |
| if (count == 0) |
| goto out; |
| |
| err = file_remove_suid(file); |
| if (err) |
| goto out; |
| |
| file_update_time(file); |
| |
| /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
| if (unlikely(file->f_flags & O_DIRECT)) { |
| loff_t endbyte; |
| ssize_t written_buffered; |
| |
| written = generic_file_direct_write(iocb, iov, &nr_segs, pos, |
| ppos, count, ocount); |
| if (written < 0 || written == count) |
| goto out; |
| /* |
| * direct-io write to a hole: fall through to buffered I/O |
| * for completing the rest of the request. |
| */ |
| pos += written; |
| count -= written; |
| written_buffered = generic_file_buffered_write(iocb, iov, |
| nr_segs, pos, ppos, count, |
| written); |
| /* |
| * If generic_file_buffered_write() retuned a synchronous error |
| * then we want to return the number of bytes which were |
| * direct-written, or the error code if that was zero. Note |
| * that this differs from normal direct-io semantics, which |
| * will return -EFOO even if some bytes were written. |
| */ |
| if (written_buffered < 0) { |
| err = written_buffered; |
| goto out; |
| } |
| |
| /* |
| * We need to ensure that the page cache pages are written to |
| * disk and invalidated to preserve the expected O_DIRECT |
| * semantics. |
| */ |
| endbyte = pos + written_buffered - written - 1; |
| err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte); |
| if (err == 0) { |
| written = written_buffered; |
| invalidate_mapping_pages(mapping, |
| pos >> PAGE_CACHE_SHIFT, |
| endbyte >> PAGE_CACHE_SHIFT); |
| } else { |
| /* |
| * We don't know how much we wrote, so just return |
| * the number of bytes which were direct-written |
| */ |
| } |
| } else { |
| written = generic_file_buffered_write(iocb, iov, nr_segs, |
| pos, ppos, count, written); |
| } |
| out: |
| current->backing_dev_info = NULL; |
| return written ? written : err; |
| } |
| EXPORT_SYMBOL(__generic_file_aio_write); |
| |
| /** |
| * generic_file_aio_write - write data to a file |
| * @iocb: IO state structure |
| * @iov: vector with data to write |
| * @nr_segs: number of segments in the vector |
| * @pos: position in file where to write |
| * |
| * This is a wrapper around __generic_file_aio_write() to be used by most |
| * filesystems. It takes care of syncing the file in case of O_SYNC file |
| * and acquires i_mutex as needed. |
| */ |
| ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
| unsigned long nr_segs, loff_t pos) |
| { |
| struct file *file = iocb->ki_filp; |
| struct inode *inode = file->f_mapping->host; |
| ssize_t ret; |
| |
| BUG_ON(iocb->ki_pos != pos); |
| |
| mutex_lock(&inode->i_mutex); |
| ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); |
| mutex_unlock(&inode->i_mutex); |
| |
| if (ret > 0 || ret == -EIOCBQUEUED) { |
| ssize_t err; |
| |
| err = generic_write_sync(file, pos, ret); |
| if (err < 0 && ret > 0) |
| ret = err; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL(generic_file_aio_write); |
| |
| /** |
| * try_to_release_page() - release old fs-specific metadata on a page |
| * |
| * @page: the page which the kernel is trying to free |
| * @gfp_mask: memory allocation flags (and I/O mode) |
| * |
| * The address_space is to try to release any data against the page |
| * (presumably at page->private). If the release was successful, return `1'. |
| * Otherwise return zero. |
| * |
| * This may also be called if PG_fscache is set on a page, indicating that the |
| * page is known to the local caching routines. |
| * |
| * The @gfp_mask argument specifies whether I/O may be performed to release |
| * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
| * |
| */ |
| int try_to_release_page(struct page *page, gfp_t gfp_mask) |
| { |
| struct address_space * const mapping = page->mapping; |
| |
| BUG_ON(!PageLocked(page)); |
| if (PageWriteback(page)) |
| return 0; |
| |
| if (mapping && mapping->a_ops->releasepage) |
| return mapping->a_ops->releasepage(page, gfp_mask); |
| return try_to_free_buffers(page); |
| } |
| |
| EXPORT_SYMBOL(try_to_release_page); |