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Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 2306 |
1 files changed, 2306 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c new file mode 100644 index 0000000..439b2be --- /dev/null +++ b/mm/filemap.c @@ -0,0 +1,2306 @@ +/* + * 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> +/* + * This is needed for the following functions: + * - try_to_release_page + * - block_invalidatepage + * - generic_osync_inode + * + * 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> + +/* + * 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_list_lock + * ->swap_device_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 (various places, mainly in mmap.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 (anon_vma_prepare and various) + * + * ->page_table_lock + * ->swap_device_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; + + if (unlikely(!PageLocked(page))) + PAGE_BUG(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); + + /* + * FIXME, fercrissake. What is this barrier here for? + */ + 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 + * + * 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. + */ +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; +} +EXPORT_SYMBOL(sync_page_range_nolock); + +/** + * 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, int 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, int 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, unsigned int 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); + unsigned int 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)) + 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); + if (!page && !nonblock) + return -ENOMEM; + if (page) { + err = install_page(mm, vma, addr, page, prot); + if (err) { + page_cache_release(page); + return err; + } + } else { + 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; +} + +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; +} +EXPORT_SYMBOL(filemap_populate); + +/* + * 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); + +/* + * Copy as much as we can into the page and return the number of bytes which + * were sucessfully copied. If a fault is encountered then clear the page + * out to (offset+bytes) and return the number of bytes which were copied. + */ +static inline size_t +filemap_copy_from_user(struct page *page, unsigned long offset, + const char __user *buf, unsigned bytes) +{ + char *kaddr; + int left; + + kaddr = kmap_atomic(page, KM_USER0); + left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); + kunmap_atomic(kaddr, KM_USER0); + + if (left != 0) { + /* Do it the slow way */ + kaddr = kmap(page); + left = __copy_from_user(kaddr + offset, buf, bytes); + kunmap(page); + } + return bytes - left; +} + +static 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; +} + +/* + * This has the same sideeffects and return value as filemap_copy_from_user(). + * The difference is that on a fault we need to memset the remainder of the + * page (out to offset+bytes), to emulate filemap_copy_from_user()'s + * single-segment behaviour. + */ +static inline size_t +filemap_copy_from_user_iovec(struct page *page, unsigned long offset, + const struct iovec *iov, size_t base, size_t bytes) +{ + char *kaddr; + size_t copied; + + kaddr = kmap_atomic(page, KM_USER0); + copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, + base, bytes); + kunmap_atomic(kaddr, KM_USER0); + if (copied != bytes) { + kaddr = kmap(page); + copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, + base, bytes); + kunmap(page); + } + return copied; +} + +static inline void +filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) +{ + const struct iovec *iov = *iovp; + size_t base = *basep; + + while (bytes) { + int copy = min(bytes, iov->iov_len - base); + + bytes -= copy; + base += copy; + if (iov->iov_len == base) { + iov++; + base = 0; + } + } + *iovp = iov; + *basep = base; +} + +/* + * 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 (unlikely(file->f_error)) { + int err = file->f_error; + file->f_error = 0; + return err; + } + + 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) + generic_osync_inode(inode, mapping, OSYNC_METADATA); + 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 = iov->iov_base + iov_base; + } + + do { + unsigned long index; + unsigned long offset; + 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. + */ + fault_in_pages_readable(buf, bytes); + + 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 (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); + +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; +} + +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. + */ +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; +} +EXPORT_SYMBOL_GPL(generic_file_direct_IO); |
