| /* |
| * 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/config.h> |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/compiler.h> |
| #include <linux/fs.h> |
| #include <linux/aio.h> |
| #include <linux/kernel_stat.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/pagevec.h> |
| #include <linux/blkdev.h> |
| #include <linux/security.h> |
| #include <linux/syscalls.h> |
| #include "filemap.h" |
| /* |
| * FIXME: remove all knowledge of the buffer layer from the core VM |
| */ |
| #include <linux/buffer_head.h> /* for generic_osync_inode */ |
| |
| #include <asm/uaccess.h> |
| #include <asm/mman.h> |
| |
| static ssize_t |
| generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
| loff_t offset, unsigned long nr_segs); |
| |
| /* |
| * 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 (vmtruncate) |
| * ->private_lock (__free_pte->__set_page_dirty_buffers) |
| * ->swap_lock (exclusive_swap_page, others) |
| * ->mapping->tree_lock |
| * |
| * ->i_sem |
| * ->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) |
| * |
| * ->mmap_sem |
| * ->i_sem (msync) |
| * |
| * ->i_sem |
| * ->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) |
| * ->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) |
| * |
| * ->task->proc_lock |
| * ->dcache_lock (proc_pid_lookup) |
| */ |
| |
| /* |
| * 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 a write_lock on 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--; |
| pagecache_acct(-1); |
| } |
| |
| void remove_from_page_cache(struct page *page) |
| { |
| struct address_space *mapping = page->mapping; |
| |
| BUG_ON(!PageLocked(page)); |
| |
| write_lock_irq(&mapping->tree_lock); |
| __remove_from_page_cache(page); |
| write_unlock_irq(&mapping->tree_lock); |
| } |
| |
| static int sync_page(void *word) |
| { |
| struct address_space *mapping; |
| struct page *page; |
| |
| page = container_of((page_flags_t *)word, struct page, flags); |
| |
| /* |
| * page_mapping() is being called without PG_locked held. |
| * Some knowledge of the state and use of the page is used to |
| * reduce the requirements down to a memory barrier. |
| * The danger here is of a stale page_mapping() return value |
| * indicating a struct address_space different from the one it's |
| * associated with when it is associated with one. |
| * After smp_mb(), it's either the correct page_mapping() for |
| * the page, or an old page_mapping() and the page's own |
| * page_mapping() has gone NULL. |
| * The ->sync_page() address_space operation must tolerate |
| * page_mapping() going NULL. By an amazing coincidence, |
| * this comes about because none of the users of the page |
| * in the ->sync_page() methods make essential use of the |
| * page_mapping(), merely passing the page down to the backing |
| * device's unplug functions when it's non-NULL, which in turn |
| * ignore it for all cases but swap, where only page_private(page) is |
| * of interest. When page_mapping() does go NULL, the entire |
| * call stack gracefully ignores the page and returns. |
| * -- wli |
| */ |
| smp_mb(); |
| mapping = page_mapping(page); |
| if (mapping && mapping->a_ops && mapping->a_ops->sync_page) |
| mapping->a_ops->sync_page(page); |
| io_schedule(); |
| return 0; |
| } |
| |
| /** |
| * filemap_fdatawrite_range - start writeback against all of a mapping's |
| * dirty pages that lie within the byte offsets <start, end> |
| * @mapping: address space structure to write |
| * @start: offset in bytes where the range starts |
| * @end: offset in bytes where the range ends |
| * @sync_mode: enable synchronous operation |
| * |
| * 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. |
| */ |
| static 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 = mapping->nrpages * 2, |
| .start = start, |
| .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, 0, sync_mode); |
| } |
| |
| int filemap_fdatawrite(struct address_space *mapping) |
| { |
| return __filemap_fdatawrite(mapping, WB_SYNC_ALL); |
| } |
| EXPORT_SYMBOL(filemap_fdatawrite); |
| |
| static int filemap_fdatawrite_range(struct address_space *mapping, |
| loff_t start, loff_t end) |
| { |
| return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); |
| } |
| |
| /* |
| * 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); |
| |
| /* |
| * Wait for writeback to complete against pages indexed by start->end |
| * inclusive |
| */ |
| static int wait_on_page_writeback_range(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| struct pagevec pvec; |
| int nr_pages; |
| int ret = 0; |
| pgoff_t index; |
| |
| if (end < start) |
| return 0; |
| |
| pagevec_init(&pvec, 0); |
| index = start; |
| 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 (PageError(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; |
| } |
| |
| /* |
| * Write and wait upon all the pages in the passed range. This is a "data |
| * integrity" operation. It waits upon in-flight writeout before starting and |
| * waiting upon new writeout. If there was an IO error, return it. |
| * |
| * We need to re-take i_sem during the generic_osync_inode list walk because |
| * it is otherwise livelockable. |
| */ |
| int sync_page_range(struct inode *inode, struct address_space *mapping, |
| loff_t pos, size_t count) |
| { |
| pgoff_t start = pos >> PAGE_CACHE_SHIFT; |
| pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; |
| int ret; |
| |
| if (!mapping_cap_writeback_dirty(mapping) || !count) |
| return 0; |
| ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); |
| if (ret == 0) { |
| down(&inode->i_sem); |
| ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
| up(&inode->i_sem); |
| } |
| if (ret == 0) |
| ret = wait_on_page_writeback_range(mapping, start, end); |
| return ret; |
| } |
| EXPORT_SYMBOL(sync_page_range); |
| |
| /* |
| * Note: Holding i_sem across sync_page_range_nolock is not a good idea |
| * as it forces O_SYNC writers to different parts of the same file |
| * to be serialised right until io completion. |
| */ |
| static int sync_page_range_nolock(struct inode *inode, |
| struct address_space *mapping, |
| loff_t pos, size_t count) |
| { |
| pgoff_t start = pos >> PAGE_CACHE_SHIFT; |
| pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; |
| int ret; |
| |
| if (!mapping_cap_writeback_dirty(mapping) || !count) |
| return 0; |
| ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); |
| if (ret == 0) |
| ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
| if (ret == 0) |
| ret = wait_on_page_writeback_range(mapping, start, end); |
| return ret; |
| } |
| |
| /** |
| * filemap_fdatawait - walk the list of under-writeback pages of the given |
| * address space and wait for all of them. |
| * |
| * @mapping: address space structure to wait for |
| */ |
| int filemap_fdatawait(struct address_space *mapping) |
| { |
| loff_t i_size = i_size_read(mapping->host); |
| |
| if (i_size == 0) |
| return 0; |
| |
| return wait_on_page_writeback_range(mapping, 0, |
| (i_size - 1) >> PAGE_CACHE_SHIFT); |
| } |
| EXPORT_SYMBOL(filemap_fdatawait); |
| |
| int filemap_write_and_wait(struct address_space *mapping) |
| { |
| int retval = 0; |
| |
| if (mapping->nrpages) { |
| retval = filemap_fdatawrite(mapping); |
| if (retval == 0) |
| retval = filemap_fdatawait(mapping); |
| } |
| return retval; |
| } |
| |
| int filemap_write_and_wait_range(struct address_space *mapping, |
| loff_t lstart, loff_t lend) |
| { |
| int retval = 0; |
| |
| if (mapping->nrpages) { |
| retval = __filemap_fdatawrite_range(mapping, lstart, lend, |
| WB_SYNC_ALL); |
| if (retval == 0) |
| retval = wait_on_page_writeback_range(mapping, |
| lstart >> PAGE_CACHE_SHIFT, |
| lend >> PAGE_CACHE_SHIFT); |
| } |
| return retval; |
| } |
| |
| /* |
| * This function is used to add newly allocated pagecache pages: |
| * the page is new, so we can just run SetPageLocked() against it. |
| * The other page state flags were set by rmqueue(). |
| * |
| * This function does not add the page to the LRU. The caller must do that. |
| */ |
| int add_to_page_cache(struct page *page, struct address_space *mapping, |
| pgoff_t offset, gfp_t gfp_mask) |
| { |
| int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
| |
| if (error == 0) { |
| write_lock_irq(&mapping->tree_lock); |
| error = radix_tree_insert(&mapping->page_tree, offset, page); |
| if (!error) { |
| page_cache_get(page); |
| SetPageLocked(page); |
| page->mapping = mapping; |
| page->index = offset; |
| mapping->nrpages++; |
| pagecache_acct(1); |
| } |
| write_unlock_irq(&mapping->tree_lock); |
| radix_tree_preload_end(); |
| } |
| return error; |
| } |
| |
| EXPORT_SYMBOL(add_to_page_cache); |
| |
| int add_to_page_cache_lru(struct page *page, struct address_space *mapping, |
| pgoff_t offset, gfp_t gfp_mask) |
| { |
| int ret = add_to_page_cache(page, mapping, offset, gfp_mask); |
| if (ret == 0) |
| lru_cache_add(page); |
| return ret; |
| } |
| |
| /* |
| * 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 fastcall 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, sync_page, |
| TASK_UNINTERRUPTIBLE); |
| } |
| EXPORT_SYMBOL(wait_on_page_bit); |
| |
| /** |
| * 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 first mb is necessary to safely close the critical section opened by the |
| * TestSetPageLocked(), the second 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 fastcall unlock_page(struct page *page) |
| { |
| smp_mb__before_clear_bit(); |
| if (!TestClearPageLocked(page)) |
| BUG(); |
| smp_mb__after_clear_bit(); |
| wake_up_page(page, PG_locked); |
| } |
| EXPORT_SYMBOL(unlock_page); |
| |
| /* |
| * End writeback against a 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); |
| |
| /* |
| * Get a lock on the page, assuming we need to sleep to get it. |
| * |
| * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
| * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
| * chances are that on the second loop, the block layer's plug list is empty, |
| * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. |
| */ |
| void fastcall __lock_page(struct page *page) |
| { |
| DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
| |
| __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, |
| TASK_UNINTERRUPTIBLE); |
| } |
| EXPORT_SYMBOL(__lock_page); |
| |
| /* |
| * a rather lightweight function, finding and getting a reference to a |
| * hashed page atomically. |
| */ |
| struct page * find_get_page(struct address_space *mapping, unsigned long offset) |
| { |
| struct page *page; |
| |
| read_lock_irq(&mapping->tree_lock); |
| page = radix_tree_lookup(&mapping->page_tree, offset); |
| if (page) |
| page_cache_get(page); |
| read_unlock_irq(&mapping->tree_lock); |
| return page; |
| } |
| |
| EXPORT_SYMBOL(find_get_page); |
| |
| /* |
| * Same as above, but trylock it instead of incrementing the count. |
| */ |
| struct page *find_trylock_page(struct address_space *mapping, unsigned long offset) |
| { |
| struct page *page; |
| |
| read_lock_irq(&mapping->tree_lock); |
| page = radix_tree_lookup(&mapping->page_tree, offset); |
| if (page && TestSetPageLocked(page)) |
| page = NULL; |
| read_unlock_irq(&mapping->tree_lock); |
| return page; |
| } |
| |
| EXPORT_SYMBOL(find_trylock_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, |
| unsigned long offset) |
| { |
| struct page *page; |
| |
| read_lock_irq(&mapping->tree_lock); |
| repeat: |
| page = radix_tree_lookup(&mapping->page_tree, offset); |
| if (page) { |
| page_cache_get(page); |
| if (TestSetPageLocked(page)) { |
| read_unlock_irq(&mapping->tree_lock); |
| lock_page(page); |
| read_lock_irq(&mapping->tree_lock); |
| |
| /* Has the page been truncated while we slept? */ |
| if (page->mapping != mapping || page->index != offset) { |
| unlock_page(page); |
| page_cache_release(page); |
| goto repeat; |
| } |
| } |
| } |
| read_unlock_irq(&mapping->tree_lock); |
| 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, |
| unsigned long index, gfp_t gfp_mask) |
| { |
| struct page *page, *cached_page = NULL; |
| int err; |
| repeat: |
| page = find_lock_page(mapping, index); |
| if (!page) { |
| if (!cached_page) { |
| cached_page = alloc_page(gfp_mask); |
| if (!cached_page) |
| return NULL; |
| } |
| err = add_to_page_cache_lru(cached_page, mapping, |
| index, gfp_mask); |
| if (!err) { |
| page = cached_page; |
| cached_page = NULL; |
| } else if (err == -EEXIST) |
| goto repeat; |
| } |
| if (cached_page) |
| page_cache_release(cached_page); |
| 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; |
| |
| read_lock_irq(&mapping->tree_lock); |
| ret = radix_tree_gang_lookup(&mapping->page_tree, |
| (void **)pages, start, nr_pages); |
| for (i = 0; i < ret; i++) |
| page_cache_get(pages[i]); |
| read_unlock_irq(&mapping->tree_lock); |
| return ret; |
| } |
| |
| /* |
| * 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; |
| |
| read_lock_irq(&mapping->tree_lock); |
| ret = radix_tree_gang_lookup_tag(&mapping->page_tree, |
| (void **)pages, *index, nr_pages, tag); |
| for (i = 0; i < ret; i++) |
| page_cache_get(pages[i]); |
| if (ret) |
| *index = pages[ret - 1]->index + 1; |
| read_unlock_irq(&mapping->tree_lock); |
| return ret; |
| } |
| |
| /* |
| * 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, unsigned long index) |
| { |
| struct page *page = find_get_page(mapping, index); |
| gfp_t gfp_mask; |
| |
| if (page) { |
| if (!TestSetPageLocked(page)) |
| return page; |
| page_cache_release(page); |
| return NULL; |
| } |
| gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS; |
| page = alloc_pages(gfp_mask, 0); |
| if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) { |
| page_cache_release(page); |
| page = NULL; |
| } |
| return page; |
| } |
| |
| EXPORT_SYMBOL(grab_cache_page_nowait); |
| |
| /* |
| * 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. |
| * |
| * Note the struct file* is only passed for the use of readpage. It may be |
| * NULL. |
| */ |
| void do_generic_mapping_read(struct address_space *mapping, |
| struct file_ra_state *_ra, |
| struct file *filp, |
| loff_t *ppos, |
| read_descriptor_t *desc, |
| read_actor_t actor) |
| { |
| struct inode *inode = mapping->host; |
| unsigned long index; |
| unsigned long end_index; |
| unsigned long offset; |
| unsigned long last_index; |
| unsigned long next_index; |
| unsigned long prev_index; |
| loff_t isize; |
| struct page *cached_page; |
| int error; |
| struct file_ra_state ra = *_ra; |
| |
| cached_page = NULL; |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| next_index = index; |
| prev_index = ra.prev_page; |
| last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
| offset = *ppos & ~PAGE_CACHE_MASK; |
| |
| isize = i_size_read(inode); |
| if (!isize) |
| goto out; |
| |
| end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
| for (;;) { |
| struct page *page; |
| unsigned long nr, ret; |
| |
| /* nr is the maximum number of bytes to copy from this page */ |
| nr = PAGE_CACHE_SIZE; |
| if (index >= end_index) { |
| if (index > end_index) |
| goto out; |
| nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
| if (nr <= offset) { |
| goto out; |
| } |
| } |
| nr = nr - offset; |
| |
| cond_resched(); |
| if (index == next_index) |
| next_index = page_cache_readahead(mapping, &ra, filp, |
| index, last_index - index); |
| |
| find_page: |
| page = find_get_page(mapping, index); |
| if (unlikely(page == NULL)) { |
| handle_ra_miss(mapping, &ra, index); |
| goto no_cached_page; |
| } |
| if (!PageUptodate(page)) |
| goto page_not_up_to_date; |
| page_ok: |
| |
| /* 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 (part of) the same page is read multiple times |
| * in succession, only mark it as accessed the first time. |
| */ |
| if (prev_index != index) |
| 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; |
| |
| page_cache_release(page); |
| if (ret == nr && desc->count) |
| continue; |
| goto out; |
| |
| page_not_up_to_date: |
| /* Get exclusive access to the page ... */ |
| lock_page(page); |
| |
| /* Did it get unhashed 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: |
| /* Start the actual read. The read will unlock the page. */ |
| error = mapping->a_ops->readpage(filp, page); |
| |
| if (unlikely(error)) |
| goto readpage_error; |
| |
| if (!PageUptodate(page)) { |
| lock_page(page); |
| if (!PageUptodate(page)) { |
| if (page->mapping == NULL) { |
| /* |
| * invalidate_inode_pages got it |
| */ |
| unlock_page(page); |
| page_cache_release(page); |
| goto find_page; |
| } |
| unlock_page(page); |
| error = -EIO; |
| goto readpage_error; |
| } |
| unlock_page(page); |
| } |
| |
| /* |
| * i_size must be checked after we have done ->readpage. |
| * |
| * Checking i_size after the readpage 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; |
| 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.. |
| */ |
| if (!cached_page) { |
| cached_page = page_cache_alloc_cold(mapping); |
| if (!cached_page) { |
| desc->error = -ENOMEM; |
| goto out; |
| } |
| } |
| error = add_to_page_cache_lru(cached_page, mapping, |
| index, GFP_KERNEL); |
| if (error) { |
| if (error == -EEXIST) |
| goto find_page; |
| desc->error = error; |
| goto out; |
| } |
| page = cached_page; |
| cached_page = NULL; |
| goto readpage; |
| } |
| |
| out: |
| *_ra = ra; |
| |
| *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
| if (cached_page) |
| page_cache_release(cached_page); |
| if (filp) |
| file_accessed(filp); |
| } |
| |
| EXPORT_SYMBOL(do_generic_mapping_read); |
| |
| 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; |
| } |
| |
| /* |
| * 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 *ppos) |
| { |
| struct file *filp = iocb->ki_filp; |
| ssize_t retval; |
| unsigned long seg; |
| size_t count; |
| |
| count = 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. |
| */ |
| count += iv->iov_len; |
| if (unlikely((ssize_t)(count|iv->iov_len) < 0)) |
| return -EINVAL; |
| if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) |
| continue; |
| if (seg == 0) |
| return -EFAULT; |
| nr_segs = seg; |
| count -= iv->iov_len; /* This segment is no good */ |
| break; |
| } |
| |
| /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
| if (filp->f_flags & O_DIRECT) { |
| loff_t pos = *ppos, size; |
| struct address_space *mapping; |
| struct inode *inode; |
| |
| mapping = filp->f_mapping; |
| inode = mapping->host; |
| retval = 0; |
| if (!count) |
| goto out; /* skip atime */ |
| size = i_size_read(inode); |
| if (pos < size) { |
| retval = generic_file_direct_IO(READ, iocb, |
| iov, pos, nr_segs); |
| if (retval > 0 && !is_sync_kiocb(iocb)) |
| retval = -EIOCBQUEUED; |
| if (retval > 0) |
| *ppos = pos + retval; |
| } |
| file_accessed(filp); |
| goto out; |
| } |
| |
| retval = 0; |
| if (count) { |
| for (seg = 0; seg < nr_segs; seg++) { |
| read_descriptor_t desc; |
| |
| desc.written = 0; |
| desc.arg.buf = iov[seg].iov_base; |
| desc.count = iov[seg].iov_len; |
| if (desc.count == 0) |
| continue; |
| desc.error = 0; |
| do_generic_file_read(filp,ppos,&desc,file_read_actor); |
| retval += desc.written; |
| if (!retval) { |
| retval = desc.error; |
| break; |
| } |
| } |
| } |
| out: |
| return retval; |
| } |
| |
| EXPORT_SYMBOL(__generic_file_aio_read); |
| |
| ssize_t |
| generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) |
| { |
| struct iovec local_iov = { .iov_base = buf, .iov_len = count }; |
| |
| BUG_ON(iocb->ki_pos != pos); |
| return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); |
| } |
| |
| EXPORT_SYMBOL(generic_file_aio_read); |
| |
| ssize_t |
| generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) |
| { |
| struct iovec local_iov = { .iov_base = buf, .iov_len = count }; |
| struct kiocb kiocb; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, filp); |
| ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); |
| if (-EIOCBQUEUED == ret) |
| ret = wait_on_sync_kiocb(&kiocb); |
| return ret; |
| } |
| |
| EXPORT_SYMBOL(generic_file_read); |
| |
| int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) |
| { |
| ssize_t written; |
| unsigned long count = desc->count; |
| struct file *file = desc->arg.data; |
| |
| if (size > count) |
| size = count; |
| |
| written = file->f_op->sendpage(file, page, offset, |
| size, &file->f_pos, size<count); |
| if (written < 0) { |
| desc->error = written; |
| written = 0; |
| } |
| desc->count = count - written; |
| desc->written += written; |
| return written; |
| } |
| |
| ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, |
| size_t count, read_actor_t actor, void *target) |
| { |
| read_descriptor_t desc; |
| |
| if (!count) |
| return 0; |
| |
| desc.written = 0; |
| desc.count = count; |
| desc.arg.data = target; |
| desc.error = 0; |
| |
| do_generic_file_read(in_file, ppos, &desc, actor); |
| if (desc.written) |
| return desc.written; |
| return desc.error; |
| } |
| |
| EXPORT_SYMBOL(generic_file_sendfile); |
| |
| static ssize_t |
| do_readahead(struct address_space *mapping, struct file *filp, |
| unsigned long index, unsigned long nr) |
| { |
| if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) |
| return -EINVAL; |
| |
| force_page_cache_readahead(mapping, filp, index, |
| max_sane_readahead(nr)); |
| return 0; |
| } |
| |
| asmlinkage ssize_t sys_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; |
| unsigned long start = offset >> PAGE_CACHE_SHIFT; |
| unsigned long 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_MMU |
| /* |
| * 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 FASTCALL(page_cache_read(struct file * file, unsigned long offset)); |
| static int fastcall page_cache_read(struct file * file, unsigned long offset) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct page *page; |
| int error; |
| |
| page = page_cache_alloc_cold(mapping); |
| if (!page) |
| return -ENOMEM; |
| |
| error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); |
| if (!error) { |
| error = mapping->a_ops->readpage(file, page); |
| page_cache_release(page); |
| return error; |
| } |
| |
| /* |
| * We arrive here in the unlikely event that someone |
| * raced with us and added our page to the cache first |
| * or we are out of memory for radix-tree nodes. |
| */ |
| page_cache_release(page); |
| return error == -EEXIST ? 0 : error; |
| } |
| |
| #define MMAP_LOTSAMISS (100) |
| |
| /* |
| * filemap_nopage() 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. |
| */ |
| struct page *filemap_nopage(struct vm_area_struct *area, |
| unsigned long address, int *type) |
| { |
| int error; |
| struct file *file = area->vm_file; |
| struct address_space *mapping = file->f_mapping; |
| struct file_ra_state *ra = &file->f_ra; |
| struct inode *inode = mapping->host; |
| struct page *page; |
| unsigned long size, pgoff; |
| int did_readaround = 0, majmin = VM_FAULT_MINOR; |
| |
| pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; |
| |
| retry_all: |
| size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| if (pgoff >= size) |
| goto outside_data_content; |
| |
| /* If we don't want any read-ahead, don't bother */ |
| if (VM_RandomReadHint(area)) |
| goto no_cached_page; |
| |
| /* |
| * The readahead code wants to be told about each and every page |
| * so it can build and shrink its windows appropriately |
| * |
| * For sequential accesses, we use the generic readahead logic. |
| */ |
| if (VM_SequentialReadHint(area)) |
| page_cache_readahead(mapping, ra, file, pgoff, 1); |
| |
| /* |
| * Do we have something in the page cache already? |
| */ |
| retry_find: |
| page = find_get_page(mapping, pgoff); |
| if (!page) { |
| unsigned long ra_pages; |
| |
| if (VM_SequentialReadHint(area)) { |
| handle_ra_miss(mapping, ra, pgoff); |
| goto no_cached_page; |
| } |
| 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 > ra->mmap_hit + MMAP_LOTSAMISS) |
| goto no_cached_page; |
| |
| /* |
| * To keep the pgmajfault counter straight, we need to |
| * check did_readaround, as this is an inner loop. |
| */ |
| if (!did_readaround) { |
| majmin = VM_FAULT_MAJOR; |
| inc_page_state(pgmajfault); |
| } |
| did_readaround = 1; |
| ra_pages = max_sane_readahead(file->f_ra.ra_pages); |
| if (ra_pages) { |
| pgoff_t start = 0; |
| |
| if (pgoff > ra_pages / 2) |
| start = pgoff - ra_pages / 2; |
| do_page_cache_readahead(mapping, file, start, ra_pages); |
| } |
| page = find_get_page(mapping, pgoff); |
| if (!page) |
| goto no_cached_page; |
| } |
| |
| if (!did_readaround) |
| ra->mmap_hit++; |
| |
| /* |
| * Ok, found a page in the page cache, now we need to check |
| * that it's up-to-date. |
| */ |
| if (!PageUptodate(page)) |
| goto page_not_uptodate; |
| |
| success: |
| /* |
| * Found the page and have a reference on it. |
| */ |
| mark_page_accessed(page); |
| if (type) |
| *type = majmin; |
| return page; |
| |
| outside_data_content: |
| /* |
| * An external ptracer can access pages that normally aren't |
| * accessible.. |
| */ |
| if (area->vm_mm == current->mm) |
| return NULL; |
| /* Fall through to the non-read-ahead case */ |
| no_cached_page: |
| /* |
| * We're only likely to ever get here if MADV_RANDOM is in |
| * effect. |
| */ |
| error = page_cache_read(file, pgoff); |
| grab_swap_token(); |
| |
| /* |
| * 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 NOPAGE_OOM; |
| return NULL; |
| |
| page_not_uptodate: |
| if (!did_readaround) { |
| majmin = VM_FAULT_MAJOR; |
| inc_page_state(pgmajfault); |
| } |
| lock_page(page); |
| |
| /* Did it get unhashed while we waited for it? */ |
| if (!page->mapping) { |
| unlock_page(page); |
| page_cache_release(page); |
| goto retry_all; |
| } |
| |
| /* Did somebody else get it up-to-date? */ |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto success; |
| } |
| |
| if (!mapping->a_ops->readpage(file, page)) { |
| wait_on_page_locked(page); |
| if (PageUptodate(page)) |
| goto success; |
| } |
| |
| /* |
| * 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. |
| */ |
| lock_page(page); |
| |
| /* Somebody truncated the page on us? */ |
| if (!page->mapping) { |
| unlock_page(page); |
| page_cache_release(page); |
| goto retry_all; |
| } |
| |
| /* Somebody else successfully read it in? */ |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto success; |
| } |
| ClearPageError(page); |
| if (!mapping->a_ops->readpage(file, page)) { |
| wait_on_page_locked(page); |
| if (PageUptodate(page)) |
| goto success; |
| } |
| |
| /* |
| * Things didn't work out. Return zero to tell the |
| * mm layer so, possibly freeing the page cache page first. |
| */ |
| page_cache_release(page); |
| return NULL; |
| } |
| |
| EXPORT_SYMBOL(filemap_nopage); |
| |
| static struct page * filemap_getpage(struct file *file, unsigned long pgoff, |
| int nonblock) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct page *page; |
| int error; |
| |
| /* |
| * Do we have something in the page cache already? |
| */ |
| retry_find: |
| page = find_get_page(mapping, pgoff); |
| if (!page) { |
| if (nonblock) |
| return NULL; |
| goto no_cached_page; |
| } |
| |
| /* |
| * Ok, found a page in the page cache, now we need to check |
| * that it's up-to-date. |
| */ |
| if (!PageUptodate(page)) { |
| if (nonblock) { |
| page_cache_release(page); |
| return NULL; |
| } |
| goto page_not_uptodate; |
| } |
| |
| success: |
| /* |
| * Found the page and have a reference on it. |
| */ |
| mark_page_accessed(page); |
| return page; |
| |
| no_cached_page: |
| error = page_cache_read(file, pgoff); |
| |
| /* |
| * 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. |
| */ |
| return NULL; |
| |
| page_not_uptodate: |
| lock_page(page); |
| |
| /* Did it get unhashed while we waited for it? */ |
| if (!page->mapping) { |
| unlock_page(page); |
| goto err; |
| } |
| |
| /* Did somebody else get it up-to-date? */ |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto success; |
| } |
| |
| if (!mapping->a_ops->readpage(file, page)) { |
| wait_on_page_locked(page); |
| if (PageUptodate(page)) |
| goto success; |
| } |
| |
| /* |
| * 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. |
| */ |
| lock_page(page); |
| |
| /* Somebody truncated the page on us? */ |
| if (!page->mapping) { |
| unlock_page(page); |
| goto err; |
| } |
| /* Somebody else successfully read it in? */ |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto success; |
| } |
| |
| ClearPageError(page); |
| if (!mapping->a_ops->readpage(file, page)) { |
| wait_on_page_locked(page); |
| if (PageUptodate(page)) |
| goto success; |
| } |
| |
| /* |
| * Things didn't work out. Return zero to tell the |
| * mm layer so, possibly freeing the page cache page first. |
| */ |
| err: |
| page_cache_release(page); |
| |
| return NULL; |
| } |
| |
| int filemap_populate(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long len, pgprot_t prot, unsigned long pgoff, |
| int nonblock) |
| { |
| struct file *file = vma->vm_file; |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| unsigned long size; |
| struct mm_struct *mm = vma->vm_mm; |
| struct page *page; |
| int err; |
| |
| if (!nonblock) |
| force_page_cache_readahead(mapping, vma->vm_file, |
| pgoff, len >> PAGE_CACHE_SHIFT); |
| |
| repeat: |
| size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) |
| return -EINVAL; |
| |
| page = filemap_getpage(file, pgoff, nonblock); |
| |
| /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as |
| * done in shmem_populate calling shmem_getpage */ |
| if (!page && !nonblock) |
| return -ENOMEM; |
| |
| if (page) { |
| err = install_page(mm, vma, addr, page, prot); |
| if (err) { |
| page_cache_release(page); |
| return err; |
| } |
| } else if (vma->vm_flags & VM_NONLINEAR) { |
| /* No page was found just because we can't read it in now (being |
| * here implies nonblock != 0), but the page may exist, so set |
| * the PTE to fault it in later. */ |
| err = install_file_pte(mm, vma, addr, pgoff, prot); |
| if (err) |
| return err; |
| } |
| |
| len -= PAGE_SIZE; |
| addr += PAGE_SIZE; |
| pgoff++; |
| if (len) |
| goto repeat; |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(filemap_populate); |
| |
| struct vm_operations_struct generic_file_vm_ops = { |
| .nopage = filemap_nopage, |
| .populate = filemap_populate, |
| }; |
| |
| /* 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; |
| 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 inline struct page *__read_cache_page(struct address_space *mapping, |
| unsigned long index, |
| int (*filler)(void *,struct page*), |
| void *data) |
| { |
| struct page *page, *cached_page = NULL; |
| int err; |
| repeat: |
| page = find_get_page(mapping, index); |
| if (!page) { |
| if (!cached_page) { |
| cached_page = page_cache_alloc_cold(mapping); |
| if (!cached_page) |
| return ERR_PTR(-ENOMEM); |
| } |
| err = add_to_page_cache_lru(cached_page, mapping, |
| index, GFP_KERNEL); |
| if (err == -EEXIST) |
| goto repeat; |
| if (err < 0) { |
| /* Presumably ENOMEM for radix tree node */ |
| page_cache_release(cached_page); |
| return ERR_PTR(err); |
| } |
| page = cached_page; |
| cached_page = NULL; |
| err = filler(data, page); |
| if (err < 0) { |
| page_cache_release(page); |
| page = ERR_PTR(err); |
| } |
| } |
| if (cached_page) |
| page_cache_release(cached_page); |
| return page; |
| } |
| |
| /* |
| * Read into the page cache. If a page already exists, |
| * and PageUptodate() is not set, try to fill the page. |
| */ |
| struct page *read_cache_page(struct address_space *mapping, |
| unsigned long index, |
| int (*filler)(void *,struct page*), |
| void *data) |
| { |
| struct page *page; |
| int err; |
| |
| retry: |
| page = __read_cache_page(mapping, index, filler, data); |
| if (IS_ERR(page)) |
| goto out; |
| mark_page_accessed(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); |
| page = ERR_PTR(err); |
| } |
| out: |
| return page; |
| } |
| |
| EXPORT_SYMBOL(read_cache_page); |
| |
| /* |
| * If the page was newly created, increment its refcount and add it to the |
| * caller's lru-buffering pagevec. This function is specifically for |
| * generic_file_write(). |
| */ |
| static inline struct page * |
| __grab_cache_page(struct address_space *mapping, unsigned long index, |
| struct page **cached_page, struct pagevec *lru_pvec) |
| { |
| int err; |
| struct page *page; |
| repeat: |
| page = find_lock_page(mapping, index); |
| if (!page) { |
| if (!*cached_page) { |
| *cached_page = page_cache_alloc(mapping); |
| if (!*cached_page) |
| return NULL; |
| } |
| err = add_to_page_cache(*cached_page, mapping, |
| index, GFP_KERNEL); |
| if (err == -EEXIST) |
| goto repeat; |
| if (err == 0) { |
| page = *cached_page; |
| page_cache_get(page); |
| if (!pagevec_add(lru_pvec, page)) |
| __pagevec_lru_add(lru_pvec); |
| *cached_page = NULL; |
| } |
| } |
| return page; |
| } |
| |
| /* |
| * The logic we want is |
| * |
| * if suid or (sgid and xgrp) |
| * remove privs |
| */ |
| int remove_suid(struct dentry *dentry) |
| { |
| mode_t mode = dentry->d_inode->i_mode; |
| int kill = 0; |
| int result = 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))) { |
| struct iattr newattrs; |
| |
| newattrs.ia_valid = ATTR_FORCE | kill; |
| result = notify_change(dentry, &newattrs); |
| } |
| return result; |
| } |
| EXPORT_SYMBOL(remove_suid); |
| |
| size_t |
| __filemap_copy_from_user_iovec(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)) { |
| /* zero the rest of the target like __copy_from_user */ |
| if (bytes) |
| memset(vaddr, 0, bytes); |
| break; |
| } |
| } |
| return copied - left; |
| } |
| |
| /* |
| * Performs necessary checks before doing a write |
| * |
| * Can adjust writing position aor 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 = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; |
| |
| 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) { |
| send_sig(SIGXFSZ, current, 0); |
| 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) { |
| send_sig(SIGXFSZ, current, 0); |
| 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 { |
| 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; |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL(generic_write_checks); |
| |
| 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; |
| |
| if (count != ocount) |
| *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); |
| |
| written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); |
| if (written > 0) { |
| loff_t end = pos + written; |
| if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { |
| i_size_write(inode, end); |
| mark_inode_dirty(inode); |
| } |
| *ppos = end; |
| } |
| |
| /* |
| * Sync the fs metadata but not the minor inode changes and |
| * of course not the data as we did direct DMA for the IO. |
| * i_sem is held, which protects generic_osync_inode() from |
| * livelocking. |
| */ |
| if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
| if (err < 0) |
| written = err; |
| } |
| if (written == count && !is_sync_kiocb(iocb)) |
| written = -EIOCBQUEUED; |
| return written; |
| } |
| EXPORT_SYMBOL(generic_file_direct_write); |
| |
| 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; |
| struct address_space * mapping = file->f_mapping; |
| struct address_space_operations *a_ops = mapping->a_ops; |
| struct inode *inode = mapping->host; |
| long status = 0; |
| struct page *page; |
| struct page *cached_page = NULL; |
| size_t bytes; |
| struct pagevec lru_pvec; |
| const struct iovec *cur_iov = iov; /* current iovec */ |
| size_t iov_base = 0; /* offset in the current iovec */ |
| char __user *buf; |
| |
| pagevec_init(&lru_pvec, 0); |
| |
| /* |
| * handle partial DIO write. Adjust cur_iov if needed. |
| */ |
| if (likely(nr_segs == 1)) |
| buf = iov->iov_base + written; |
| else { |
| filemap_set_next_iovec(&cur_iov, &iov_base, written); |
| buf = cur_iov->iov_base + iov_base; |
| } |
| |
| do { |
| unsigned long index; |
| unsigned long offset; |
| unsigned long maxlen; |
| size_t copied; |
| |
| offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ |
| index = pos >> PAGE_CACHE_SHIFT; |
| bytes = PAGE_CACHE_SIZE - offset; |
| if (bytes > count) |
| bytes = count; |
| |
| /* |
| * 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. |
| */ |
| maxlen = cur_iov->iov_len - iov_base; |
| if (maxlen > bytes) |
| maxlen = bytes; |
| fault_in_pages_readable(buf, maxlen); |
| |
| page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); |
| if (!page) { |
| status = -ENOMEM; |
| break; |
| } |
| |
| status = a_ops->prepare_write(file, page, offset, offset+bytes); |
| if (unlikely(status)) { |
| loff_t isize = i_size_read(inode); |
| /* |
| * prepare_write() may have instantiated a few blocks |
| * outside i_size. Trim these off again. |
| */ |
| unlock_page(page); |
| page_cache_release(page); |
| if (pos + bytes > isize) |
| vmtruncate(inode, isize); |
| break; |
| } |
| if (likely(nr_segs == 1)) |
| copied = filemap_copy_from_user(page, offset, |
| buf, bytes); |
| else |
| copied = filemap_copy_from_user_iovec(page, offset, |
| cur_iov, iov_base, bytes); |
| flush_dcache_page(page); |
| status = a_ops->commit_write(file, page, offset, offset+bytes); |
| if (likely(copied > 0)) { |
| if (!status) |
| status = copied; |
| |
| if (status >= 0) { |
| written += status; |
| count -= status; |
| pos += status; |
| buf += status; |
| if (unlikely(nr_segs > 1)) { |
| filemap_set_next_iovec(&cur_iov, |
| &iov_base, status); |
| if (count) |
| buf = cur_iov->iov_base + |
| iov_base; |
| } else { |
| iov_base += status; |
| } |
| } |
| } |
| if (unlikely(copied != bytes)) |
| if (status >= 0) |
| status = -EFAULT; |
| unlock_page(page); |
| mark_page_accessed(page); |
| page_cache_release(page); |
| if (status < 0) |
| break; |
| balance_dirty_pages_ratelimited(mapping); |
| cond_resched(); |
| } while (count); |
| *ppos = pos; |
| |
| if (cached_page) |
| page_cache_release(cached_page); |
| |
| /* |
| * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC |
| */ |
| if (likely(status >= 0)) { |
| if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| if (!a_ops->writepage || !is_sync_kiocb(iocb)) |
| status = generic_osync_inode(inode, mapping, |
| OSYNC_METADATA|OSYNC_DATA); |
| } |
| } |
| |
| /* |
| * If we get here for O_DIRECT writes then we must have fallen through |
| * to buffered writes (block instantiation inside i_size). So we sync |
| * the file data here, to try to honour O_DIRECT expectations. |
| */ |
| if (unlikely(file->f_flags & O_DIRECT) && written) |
| status = filemap_write_and_wait(mapping); |
| |
| pagevec_lru_add(&lru_pvec); |
| return written ? written : status; |
| } |
| EXPORT_SYMBOL(generic_file_buffered_write); |
| |
| static ssize_t |
| __generic_file_aio_write_nolock(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; |
| unsigned long seg; |
| loff_t pos; |
| ssize_t written; |
| ssize_t err; |
| |
| ocount = 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. |
| */ |
| ocount += iv->iov_len; |
| if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) |
| return -EINVAL; |
| if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) |
| continue; |
| if (seg == 0) |
| return -EFAULT; |
| nr_segs = seg; |
| ocount -= iv->iov_len; /* This segment is no good */ |
| break; |
| } |
| |
| 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 = remove_suid(file->f_dentry); |
| if (err) |
| goto out; |
| |
| inode_update_time(inode, 1); |
| |
| /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
| if (unlikely(file->f_flags & O_DIRECT)) { |
| 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 = 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_nolock); |
| |
| ssize_t |
| generic_file_aio_write_nolock(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; |
| struct inode *inode = mapping->host; |
| ssize_t ret; |
| loff_t pos = *ppos; |
| |
| ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos); |
| |
| if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| int err; |
| |
| err = sync_page_range_nolock(inode, mapping, pos, ret); |
| if (err < 0) |
| ret = err; |
| } |
| return ret; |
| } |
| |
| static ssize_t |
| __generic_file_write_nolock(struct file *file, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct kiocb kiocb; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, file); |
| ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); |
| if (ret == -EIOCBQUEUED) |
| ret = wait_on_sync_kiocb(&kiocb); |
| return ret; |
| } |
| |
| ssize_t |
| generic_file_write_nolock(struct file *file, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct kiocb kiocb; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, file); |
| ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); |
| if (-EIOCBQUEUED == ret) |
| ret = wait_on_sync_kiocb(&kiocb); |
| return ret; |
| } |
| EXPORT_SYMBOL(generic_file_write_nolock); |
| |
| ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf, |
| size_t count, loff_t pos) |
| { |
| struct file *file = iocb->ki_filp; |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| ssize_t ret; |
| struct iovec local_iov = { .iov_base = (void __user *)buf, |
| .iov_len = count }; |
| |
| BUG_ON(iocb->ki_pos != pos); |
| |
| down(&inode->i_sem); |
| ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1, |
| &iocb->ki_pos); |
| up(&inode->i_sem); |
| |
| if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| ssize_t err; |
| |
| err = sync_page_range(inode, mapping, pos, ret); |
| if (err < 0) |
| ret = err; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL(generic_file_aio_write); |
| |
| ssize_t generic_file_write(struct file *file, const char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| ssize_t ret; |
| struct iovec local_iov = { .iov_base = (void __user *)buf, |
| .iov_len = count }; |
| |
| down(&inode->i_sem); |
| ret = __generic_file_write_nolock(file, &local_iov, 1, ppos); |
| up(&inode->i_sem); |
| |
| if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| ssize_t err; |
| |
| err = sync_page_range(inode, mapping, *ppos - ret, ret); |
| if (err < 0) |
| ret = err; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL(generic_file_write); |
| |
| ssize_t generic_file_readv(struct file *filp, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct kiocb kiocb; |
| ssize_t ret; |
| |
| init_sync_kiocb(&kiocb, filp); |
| ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos); |
| if (-EIOCBQUEUED == ret) |
| ret = wait_on_sync_kiocb(&kiocb); |
| return ret; |
| } |
| EXPORT_SYMBOL(generic_file_readv); |
| |
| ssize_t generic_file_writev(struct file *file, const struct iovec *iov, |
| unsigned long nr_segs, loff_t *ppos) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| ssize_t ret; |
| |
| down(&inode->i_sem); |
| ret = __generic_file_write_nolock(file, iov, nr_segs, ppos); |
| up(&inode->i_sem); |
| |
| if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| int err; |
| |
| err = sync_page_range(inode, mapping, *ppos - ret, ret); |
| if (err < 0) |
| ret = err; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL(generic_file_writev); |
| |
| /* |
| * Called under i_sem for writes to S_ISREG files. Returns -EIO if something |
| * went wrong during pagecache shootdown. |
| */ |
| static ssize_t |
| generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
| loff_t offset, unsigned long nr_segs) |
| { |
| struct file *file = iocb->ki_filp; |
| struct address_space *mapping = file->f_mapping; |
| ssize_t retval; |
| size_t write_len = 0; |
| |
| /* |
| * If it's a write, unmap all mmappings of the file up-front. This |
| * will cause any pte dirty bits to be propagated into the pageframes |
| * for the subsequent filemap_write_and_wait(). |
| */ |
| if (rw == WRITE) { |
| write_len = iov_length(iov, nr_segs); |
| if (mapping_mapped(mapping)) |
| unmap_mapping_range(mapping, offset, write_len, 0); |
| } |
| |
| retval = filemap_write_and_wait(mapping); |
| if (retval == 0) { |
| retval = mapping->a_ops->direct_IO(rw, iocb, iov, |
| offset, nr_segs); |
| if (rw == WRITE && mapping->nrpages) { |
| pgoff_t end = (offset + write_len - 1) |
| >> PAGE_CACHE_SHIFT; |
| int err = invalidate_inode_pages2_range(mapping, |
| offset >> PAGE_CACHE_SHIFT, end); |
| if (err) |
| retval = err; |
| } |
| } |
| return retval; |
| } |