if (PageSwapBacked(page)) {
__mod_lruvec_page_state(page, NR_SHMEM, -nr);
if (PageTransHuge(page))
- __dec_lruvec_page_state(page, NR_SHMEM_THPS);
+ __mod_lruvec_page_state(page, NR_SHMEM_THPS, -nr);
} else if (PageTransHuge(page)) {
- __dec_lruvec_page_state(page, NR_FILE_THPS);
+ __mod_lruvec_page_state(page, NR_FILE_THPS, -nr);
filemap_nr_thps_dec(mapping);
}
* replace_page_cache_page - replace a pagecache page with a new one
* @old: page to be replaced
* @new: page to replace with
- * @gfp_mask: allocation mode
*
* This function replaces a page in the pagecache with a new one. On
* success it acquires the pagecache reference for the new page and
* caller must do that.
*
* The remove + add is atomic. This function cannot fail.
- *
- * Return: %0
*/
-int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
+void replace_page_cache_page(struct page *old, struct page *new)
{
struct address_space *mapping = old->mapping;
void (*freepage)(struct page *) = mapping->a_ops->freepage;
if (freepage)
freepage(old);
put_page(old);
-
- return 0;
}
EXPORT_SYMBOL_GPL(replace_page_cache_page);
}
EXPORT_SYMBOL(wait_on_page_bit_killable);
-static int __wait_on_page_locked_async(struct page *page,
- struct wait_page_queue *wait, bool set)
-{
- struct wait_queue_head *q = page_waitqueue(page);
- int ret = 0;
-
- wait->page = page;
- wait->bit_nr = PG_locked;
-
- spin_lock_irq(&q->lock);
- __add_wait_queue_entry_tail(q, &wait->wait);
- SetPageWaiters(page);
- if (set)
- ret = !trylock_page(page);
- else
- ret = PageLocked(page);
- /*
- * If we were successful now, we know we're still on the
- * waitqueue as we're still under the lock. This means it's
- * safe to remove and return success, we know the callback
- * isn't going to trigger.
- */
- if (!ret)
- __remove_wait_queue(q, &wait->wait);
- else
- ret = -EIOCBQUEUED;
- spin_unlock_irq(&q->lock);
- return ret;
-}
-
-static int wait_on_page_locked_async(struct page *page,
- struct wait_page_queue *wait)
-{
- if (!PageLocked(page))
- return 0;
- return __wait_on_page_locked_async(compound_head(page), wait, false);
-}
-
/**
* put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked
* @page: The page to wait for.
+ * @state: The sleep state (TASK_KILLABLE, TASK_UNINTERRUPTIBLE, etc).
*
* The caller should hold a reference on @page. They expect the page to
* become unlocked relatively soon, but do not wish to hold up migration
* (for example) by holding the reference while waiting for the page to
* come unlocked. After this function returns, the caller should not
* dereference @page.
+ *
+ * Return: 0 if the page was unlocked or -EINTR if interrupted by a signal.
*/
-void put_and_wait_on_page_locked(struct page *page)
+int put_and_wait_on_page_locked(struct page *page, int state)
{
wait_queue_head_t *q;
page = compound_head(page);
q = page_waitqueue(page);
- wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE, DROP);
+ return wait_on_page_bit_common(q, page, PG_locked, state, DROP);
}
/**
int __lock_page_async(struct page *page, struct wait_page_queue *wait)
{
- return __wait_on_page_locked_async(page, wait, true);
+ struct wait_queue_head *q = page_waitqueue(page);
+ int ret = 0;
+
+ wait->page = page;
+ wait->bit_nr = PG_locked;
+
+ spin_lock_irq(&q->lock);
+ __add_wait_queue_entry_tail(q, &wait->wait);
+ SetPageWaiters(page);
+ ret = !trylock_page(page);
+ /*
+ * If we were successful now, we know we're still on the
+ * waitqueue as we're still under the lock. This means it's
+ * safe to remove and return success, we know the callback
+ * isn't going to trigger.
+ */
+ if (!ret)
+ __remove_wait_queue(q, &wait->wait);
+ else
+ ret = -EIOCBQUEUED;
+ spin_unlock_irq(&q->lock);
+ return ret;
}
/*
}
EXPORT_SYMBOL(page_cache_prev_miss);
-/**
- * find_get_entry - find and get a page cache entry
+/*
+ * mapping_get_entry - Get a page cache entry.
* @mapping: the address_space to search
* @index: The page cache index.
*
*
* Return: The head page or shadow entry, %NULL if nothing is found.
*/
-struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
+static struct page *mapping_get_entry(struct address_space *mapping,
+ pgoff_t index)
{
XA_STATE(xas, &mapping->i_pages, index);
struct page *page;
return page;
}
-/**
- * find_lock_entry - Locate and lock a page cache entry.
- * @mapping: The address_space to search.
- * @index: The page cache index.
- *
- * Looks up the page at @mapping & @index. If there is a page in the
- * cache, the head page is returned locked and with an increased refcount.
- *
- * If the slot holds a shadow entry of a previously evicted page, or a
- * swap entry from shmem/tmpfs, it is returned.
- *
- * Context: May sleep.
- * Return: The head page or shadow entry, %NULL if nothing is found.
- */
-struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
-{
- struct page *page;
-
-repeat:
- page = find_get_entry(mapping, index);
- if (page && !xa_is_value(page)) {
- lock_page(page);
- /* Has the page been truncated? */
- if (unlikely(page->mapping != mapping)) {
- unlock_page(page);
- put_page(page);
- goto repeat;
- }
- VM_BUG_ON_PAGE(!thp_contains(page, index), page);
- }
- return page;
-}
-
/**
* pagecache_get_page - Find and get a reference to a page.
* @mapping: The address_space to search.
* * %FGP_LOCK - The page is returned locked.
* * %FGP_HEAD - If the page is present and a THP, return the head page
* rather than the exact page specified by the index.
+ * * %FGP_ENTRY - If there is a shadow / swap / DAX entry, return it
+ * instead of allocating a new page to replace it.
* * %FGP_CREAT - If no page is present then a new page is allocated using
* @gfp_mask and added to the page cache and the VM's LRU list.
* The page is returned locked and with an increased refcount.
struct page *page;
repeat:
- page = find_get_entry(mapping, index);
- if (xa_is_value(page))
+ page = mapping_get_entry(mapping, index);
+ if (xa_is_value(page)) {
+ if (fgp_flags & FGP_ENTRY)
+ return page;
page = NULL;
+ }
if (!page)
goto no_page;
}
EXPORT_SYMBOL(pagecache_get_page);
+static inline struct page *find_get_entry(struct xa_state *xas, pgoff_t max,
+ xa_mark_t mark)
+{
+ struct page *page;
+
+retry:
+ if (mark == XA_PRESENT)
+ page = xas_find(xas, max);
+ else
+ page = xas_find_marked(xas, max, mark);
+
+ if (xas_retry(xas, page))
+ goto retry;
+ /*
+ * A shadow entry of a recently evicted page, a swap
+ * entry from shmem/tmpfs or a DAX entry. Return it
+ * without attempting to raise page count.
+ */
+ if (!page || xa_is_value(page))
+ return page;
+
+ if (!page_cache_get_speculative(page))
+ goto reset;
+
+ /* Has the page moved or been split? */
+ if (unlikely(page != xas_reload(xas))) {
+ put_page(page);
+ goto reset;
+ }
+
+ return page;
+reset:
+ xas_reset(xas);
+ goto retry;
+}
+
/**
* find_get_entries - gang pagecache lookup
* @mapping: The address_space to search
* @start: The starting page cache index
- * @nr_entries: The maximum number of entries
- * @entries: Where the resulting entries are placed
+ * @end: The final page index (inclusive).
+ * @pvec: Where the resulting entries are placed.
* @indices: The cache indices corresponding to the entries in @entries
*
- * find_get_entries() will search for and return a group of up to
- * @nr_entries entries in the mapping. The entries are placed at
- * @entries. find_get_entries() takes a reference against any actual
- * pages it returns.
+ * find_get_entries() will search for and return a batch of entries in
+ * the mapping. The entries are placed in @pvec. find_get_entries()
+ * takes a reference on any actual pages it returns.
*
* The search returns a group of mapping-contiguous page cache entries
* with ascending indexes. There may be holes in the indices due to
*
* Return: the number of pages and shadow entries which were found.
*/
-unsigned find_get_entries(struct address_space *mapping,
- pgoff_t start, unsigned int nr_entries,
- struct page **entries, pgoff_t *indices)
+unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
+ pgoff_t end, struct pagevec *pvec, pgoff_t *indices)
{
XA_STATE(xas, &mapping->i_pages, start);
struct page *page;
unsigned int ret = 0;
-
- if (!nr_entries)
- return 0;
+ unsigned nr_entries = PAGEVEC_SIZE;
rcu_read_lock();
- xas_for_each(&xas, page, ULONG_MAX) {
- if (xas_retry(&xas, page))
- continue;
- /*
- * A shadow entry of a recently evicted page, a swap
- * entry from shmem/tmpfs or a DAX entry. Return it
- * without attempting to raise page count.
- */
- if (xa_is_value(page))
- goto export;
-
- if (!page_cache_get_speculative(page))
- goto retry;
-
- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(&xas)))
- goto put_page;
-
+ while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
/*
* Terminate early on finding a THP, to allow the caller to
* handle it all at once; but continue if this is hugetlbfs.
*/
- if (PageTransHuge(page) && !PageHuge(page)) {
+ if (!xa_is_value(page) && PageTransHuge(page) &&
+ !PageHuge(page)) {
page = find_subpage(page, xas.xa_index);
nr_entries = ret + 1;
}
-export:
+
indices[ret] = xas.xa_index;
- entries[ret] = page;
+ pvec->pages[ret] = page;
if (++ret == nr_entries)
break;
- continue;
-put_page:
- put_page(page);
-retry:
- xas_reset(&xas);
}
rcu_read_unlock();
+
+ pvec->nr = ret;
return ret;
}
+/**
+ * find_lock_entries - Find a batch of pagecache entries.
+ * @mapping: The address_space to search.
+ * @start: The starting page cache index.
+ * @end: The final page index (inclusive).
+ * @pvec: Where the resulting entries are placed.
+ * @indices: The cache indices of the entries in @pvec.
+ *
+ * find_lock_entries() will return a batch of entries from @mapping.
+ * Swap, shadow and DAX entries are included. Pages are returned
+ * locked and with an incremented refcount. Pages which are locked by
+ * somebody else or under writeback are skipped. Only the head page of
+ * a THP is returned. Pages which are partially outside the range are
+ * not returned.
+ *
+ * The entries have ascending indexes. The indices may not be consecutive
+ * due to not-present entries, THP pages, pages which could not be locked
+ * or pages under writeback.
+ *
+ * Return: The number of entries which were found.
+ */
+unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
+ pgoff_t end, struct pagevec *pvec, pgoff_t *indices)
+{
+ XA_STATE(xas, &mapping->i_pages, start);
+ struct page *page;
+
+ rcu_read_lock();
+ while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
+ if (!xa_is_value(page)) {
+ if (page->index < start)
+ goto put;
+ VM_BUG_ON_PAGE(page->index != xas.xa_index, page);
+ if (page->index + thp_nr_pages(page) - 1 > end)
+ goto put;
+ if (!trylock_page(page))
+ goto put;
+ if (page->mapping != mapping || PageWriteback(page))
+ goto unlock;
+ VM_BUG_ON_PAGE(!thp_contains(page, xas.xa_index),
+ page);
+ }
+ indices[pvec->nr] = xas.xa_index;
+ if (!pagevec_add(pvec, page))
+ break;
+ goto next;
+unlock:
+ unlock_page(page);
+put:
+ put_page(page);
+next:
+ if (!xa_is_value(page) && PageTransHuge(page))
+ xas_set(&xas, page->index + thp_nr_pages(page));
+ }
+ rcu_read_unlock();
+
+ return pagevec_count(pvec);
+}
+
/**
* find_get_pages_range - gang pagecache lookup
* @mapping: The address_space to search
return 0;
rcu_read_lock();
- xas_for_each(&xas, page, end) {
- if (xas_retry(&xas, page))
- continue;
+ while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
/* Skip over shadow, swap and DAX entries */
if (xa_is_value(page))
continue;
- if (!page_cache_get_speculative(page))
- goto retry;
-
- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(&xas)))
- goto put_page;
-
pages[ret] = find_subpage(page, xas.xa_index);
if (++ret == nr_pages) {
*start = xas.xa_index + 1;
goto out;
}
- continue;
-put_page:
- put_page(page);
-retry:
- xas_reset(&xas);
}
/*
EXPORT_SYMBOL(find_get_pages_contig);
/**
- * find_get_pages_range_tag - find and return pages in given range matching @tag
+ * find_get_pages_range_tag - Find and return head pages matching @tag.
* @mapping: the address_space to search
* @index: the starting page index
* @end: The final page index (inclusive)
* @nr_pages: the maximum number of pages
* @pages: where the resulting pages are placed
*
- * Like find_get_pages, except we only return pages which are tagged with
- * @tag. We update @index to index the next page for the traversal.
+ * Like find_get_pages(), except we only return head pages which are tagged
+ * with @tag. @index is updated to the index immediately after the last
+ * page we return, ready for the next iteration.
*
* Return: the number of pages which were found.
*/
return 0;
rcu_read_lock();
- xas_for_each_marked(&xas, page, end, tag) {
- if (xas_retry(&xas, page))
- continue;
+ while ((page = find_get_entry(&xas, end, tag))) {
/*
* Shadow entries should never be tagged, but this iteration
* is lockless so there is a window for page reclaim to evict
if (xa_is_value(page))
continue;
- if (!page_cache_get_speculative(page))
- goto retry;
-
- /* Has the page moved or been split? */
- if (unlikely(page != xas_reload(&xas)))
- goto put_page;
-
- pages[ret] = find_subpage(page, xas.xa_index);
+ pages[ret] = page;
if (++ret == nr_pages) {
- *index = xas.xa_index + 1;
+ *index = page->index + thp_nr_pages(page);
goto out;
}
- continue;
-put_page:
- put_page(page);
-retry:
- xas_reset(&xas);
}
/*
ra->ra_pages /= 4;
}
-static int lock_page_for_iocb(struct kiocb *iocb, struct page *page)
+/*
+ * filemap_get_read_batch - Get a batch of pages for read
+ *
+ * Get a batch of pages which represent a contiguous range of bytes
+ * in the file. No tail pages will be returned. If @index is in the
+ * middle of a THP, the entire THP will be returned. The last page in
+ * the batch may have Readahead set or be not Uptodate so that the
+ * caller can take the appropriate action.
+ */
+static void filemap_get_read_batch(struct address_space *mapping,
+ pgoff_t index, pgoff_t max, struct pagevec *pvec)
{
- if (iocb->ki_flags & IOCB_WAITQ)
- return lock_page_async(page, iocb->ki_waitq);
- else if (iocb->ki_flags & IOCB_NOWAIT)
- return trylock_page(page) ? 0 : -EAGAIN;
- else
- return lock_page_killable(page);
+ XA_STATE(xas, &mapping->i_pages, index);
+ struct page *head;
+
+ rcu_read_lock();
+ for (head = xas_load(&xas); head; head = xas_next(&xas)) {
+ if (xas_retry(&xas, head))
+ continue;
+ if (xas.xa_index > max || xa_is_value(head))
+ break;
+ if (!page_cache_get_speculative(head))
+ goto retry;
+
+ /* Has the page moved or been split? */
+ if (unlikely(head != xas_reload(&xas)))
+ goto put_page;
+
+ if (!pagevec_add(pvec, head))
+ break;
+ if (!PageUptodate(head))
+ break;
+ if (PageReadahead(head))
+ break;
+ xas.xa_index = head->index + thp_nr_pages(head) - 1;
+ xas.xa_offset = (xas.xa_index >> xas.xa_shift) & XA_CHUNK_MASK;
+ continue;
+put_page:
+ put_page(head);
+retry:
+ xas_reset(&xas);
+ }
+ rcu_read_unlock();
}
-static struct page *
-generic_file_buffered_read_readpage(struct kiocb *iocb,
- struct file *filp,
- struct address_space *mapping,
- struct page *page)
+static int filemap_read_page(struct file *file, struct address_space *mapping,
+ struct page *page)
{
- struct file_ra_state *ra = &filp->f_ra;
int error;
- if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT)) {
- unlock_page(page);
- put_page(page);
- return ERR_PTR(-EAGAIN);
- }
-
/*
- * A previous I/O error may have been due to temporary
- * failures, eg. multipath errors.
- * PG_error will be set again if readpage fails.
+ * A previous I/O error may have been due to temporary failures,
+ * eg. multipath errors. PG_error will be set again if readpage
+ * fails.
*/
ClearPageError(page);
/* Start the actual read. The read will unlock the page. */
- error = mapping->a_ops->readpage(filp, page);
+ error = mapping->a_ops->readpage(file, page);
+ if (error)
+ return error;
- if (unlikely(error)) {
- put_page(page);
- return error != AOP_TRUNCATED_PAGE ? ERR_PTR(error) : NULL;
- }
+ error = wait_on_page_locked_killable(page);
+ if (error)
+ return error;
+ if (PageUptodate(page))
+ return 0;
+ if (!page->mapping) /* page truncated */
+ return AOP_TRUNCATED_PAGE;
+ shrink_readahead_size_eio(&file->f_ra);
+ return -EIO;
+}
- if (!PageUptodate(page)) {
- error = lock_page_for_iocb(iocb, page);
- if (unlikely(error)) {
- put_page(page);
- return ERR_PTR(error);
- }
- if (!PageUptodate(page)) {
- if (page->mapping == NULL) {
- /*
- * invalidate_mapping_pages got it
- */
- unlock_page(page);
- put_page(page);
- return NULL;
- }
- unlock_page(page);
- shrink_readahead_size_eio(ra);
- put_page(page);
- return ERR_PTR(-EIO);
- }
- unlock_page(page);
+static bool filemap_range_uptodate(struct address_space *mapping,
+ loff_t pos, struct iov_iter *iter, struct page *page)
+{
+ int count;
+
+ if (PageUptodate(page))
+ return true;
+ /* pipes can't handle partially uptodate pages */
+ if (iov_iter_is_pipe(iter))
+ return false;
+ if (!mapping->a_ops->is_partially_uptodate)
+ return false;
+ if (mapping->host->i_blkbits >= (PAGE_SHIFT + thp_order(page)))
+ return false;
+
+ count = iter->count;
+ if (page_offset(page) > pos) {
+ count -= page_offset(page) - pos;
+ pos = 0;
+ } else {
+ pos -= page_offset(page);
}
- return page;
+ return mapping->a_ops->is_partially_uptodate(page, pos, count);
}
-static struct page *
-generic_file_buffered_read_pagenotuptodate(struct kiocb *iocb,
- struct file *filp,
- struct iov_iter *iter,
- struct page *page,
- loff_t pos, loff_t count)
+static int filemap_update_page(struct kiocb *iocb,
+ struct address_space *mapping, struct iov_iter *iter,
+ struct page *page)
{
- struct address_space *mapping = filp->f_mapping;
- struct inode *inode = mapping->host;
int error;
- /*
- * See comment in do_read_cache_page on why
- * wait_on_page_locked is used to avoid unnecessarily
- * serialisations and why it's safe.
- */
- if (iocb->ki_flags & IOCB_WAITQ) {
- error = wait_on_page_locked_async(page,
- iocb->ki_waitq);
- } else {
- error = wait_on_page_locked_killable(page);
- }
- if (unlikely(error)) {
- put_page(page);
- return ERR_PTR(error);
+ if (!trylock_page(page)) {
+ if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO))
+ return -EAGAIN;
+ if (!(iocb->ki_flags & IOCB_WAITQ)) {
+ put_and_wait_on_page_locked(page, TASK_KILLABLE);
+ return AOP_TRUNCATED_PAGE;
+ }
+ error = __lock_page_async(page, iocb->ki_waitq);
+ if (error)
+ return error;
}
- if (PageUptodate(page))
- return page;
- if (inode->i_blkbits == PAGE_SHIFT ||
- !mapping->a_ops->is_partially_uptodate)
- goto page_not_up_to_date;
- /* pipes can't handle partially uptodate pages */
- if (unlikely(iov_iter_is_pipe(iter)))
- goto page_not_up_to_date;
- if (!trylock_page(page))
- goto page_not_up_to_date;
- /* Did it get truncated before we got the lock? */
if (!page->mapping)
- goto page_not_up_to_date_locked;
- if (!mapping->a_ops->is_partially_uptodate(page,
- pos & ~PAGE_MASK, count))
- goto page_not_up_to_date_locked;
- unlock_page(page);
- return page;
-
-page_not_up_to_date:
- /* Get exclusive access to the page ... */
- error = lock_page_for_iocb(iocb, page);
- if (unlikely(error)) {
- put_page(page);
- return ERR_PTR(error);
- }
+ goto truncated;
-page_not_up_to_date_locked:
- /* Did it get truncated before we got the lock? */
- if (!page->mapping) {
- unlock_page(page);
- put_page(page);
- return NULL;
- }
+ error = 0;
+ if (filemap_range_uptodate(mapping, iocb->ki_pos, iter, page))
+ goto unlock;
- /* Did somebody else fill it already? */
- if (PageUptodate(page)) {
- unlock_page(page);
- return page;
- }
+ error = -EAGAIN;
+ if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
+ goto unlock;
- return generic_file_buffered_read_readpage(iocb, filp, mapping, page);
+ error = filemap_read_page(iocb->ki_filp, mapping, page);
+ if (error == AOP_TRUNCATED_PAGE)
+ put_page(page);
+ return error;
+truncated:
+ unlock_page(page);
+ put_page(page);
+ return AOP_TRUNCATED_PAGE;
+unlock:
+ unlock_page(page);
+ return error;
}
-static struct page *
-generic_file_buffered_read_no_cached_page(struct kiocb *iocb,
- struct iov_iter *iter)
+static int filemap_create_page(struct file *file,
+ struct address_space *mapping, pgoff_t index,
+ struct pagevec *pvec)
{
- struct file *filp = iocb->ki_filp;
- struct address_space *mapping = filp->f_mapping;
- pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
struct page *page;
int error;
- if (iocb->ki_flags & IOCB_NOIO)
- return ERR_PTR(-EAGAIN);
-
- /*
- * Ok, it wasn't cached, so we need to create a new
- * page..
- */
page = page_cache_alloc(mapping);
if (!page)
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
error = add_to_page_cache_lru(page, mapping, index,
- mapping_gfp_constraint(mapping, GFP_KERNEL));
- if (error) {
- put_page(page);
- return error != -EEXIST ? ERR_PTR(error) : NULL;
- }
+ mapping_gfp_constraint(mapping, GFP_KERNEL));
+ if (error == -EEXIST)
+ error = AOP_TRUNCATED_PAGE;
+ if (error)
+ goto error;
+
+ error = filemap_read_page(file, mapping, page);
+ if (error)
+ goto error;
- return generic_file_buffered_read_readpage(iocb, filp, mapping, page);
+ pagevec_add(pvec, page);
+ return 0;
+error:
+ put_page(page);
+ return error;
+}
+
+static int filemap_readahead(struct kiocb *iocb, struct file *file,
+ struct address_space *mapping, struct page *page,
+ pgoff_t last_index)
+{
+ if (iocb->ki_flags & IOCB_NOIO)
+ return -EAGAIN;
+ page_cache_async_readahead(mapping, &file->f_ra, file, page,
+ page->index, last_index - page->index);
+ return 0;
}
-static int generic_file_buffered_read_get_pages(struct kiocb *iocb,
- struct iov_iter *iter,
- struct page **pages,
- unsigned int nr)
+static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
+ struct pagevec *pvec)
{
struct file *filp = iocb->ki_filp;
struct address_space *mapping = filp->f_mapping;
struct file_ra_state *ra = &filp->f_ra;
pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
- pgoff_t last_index = (iocb->ki_pos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT;
- int i, j, nr_got, err = 0;
+ pgoff_t last_index;
+ struct page *page;
+ int err = 0;
- nr = min_t(unsigned long, last_index - index, nr);
-find_page:
+ last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE);
+retry:
if (fatal_signal_pending(current))
return -EINTR;
- nr_got = find_get_pages_contig(mapping, index, nr, pages);
- if (nr_got)
- goto got_pages;
-
- if (iocb->ki_flags & IOCB_NOIO)
- return -EAGAIN;
-
- page_cache_sync_readahead(mapping, ra, filp, index, last_index - index);
-
- nr_got = find_get_pages_contig(mapping, index, nr, pages);
- if (nr_got)
- goto got_pages;
-
- pages[0] = generic_file_buffered_read_no_cached_page(iocb, iter);
- err = PTR_ERR_OR_ZERO(pages[0]);
- if (!IS_ERR_OR_NULL(pages[0]))
- nr_got = 1;
-got_pages:
- for (i = 0; i < nr_got; i++) {
- struct page *page = pages[i];
- pgoff_t pg_index = index + i;
- loff_t pg_pos = max(iocb->ki_pos,
- (loff_t) pg_index << PAGE_SHIFT);
- loff_t pg_count = iocb->ki_pos + iter->count - pg_pos;
-
- if (PageReadahead(page)) {
- if (iocb->ki_flags & IOCB_NOIO) {
- for (j = i; j < nr_got; j++)
- put_page(pages[j]);
- nr_got = i;
- err = -EAGAIN;
- break;
- }
- page_cache_async_readahead(mapping, ra, filp, page,
- pg_index, last_index - pg_index);
- }
-
- if (!PageUptodate(page)) {
- if ((iocb->ki_flags & IOCB_NOWAIT) ||
- ((iocb->ki_flags & IOCB_WAITQ) && i)) {
- for (j = i; j < nr_got; j++)
- put_page(pages[j]);
- nr_got = i;
- err = -EAGAIN;
- break;
- }
+ filemap_get_read_batch(mapping, index, last_index, pvec);
+ if (!pagevec_count(pvec)) {
+ if (iocb->ki_flags & IOCB_NOIO)
+ return -EAGAIN;
+ page_cache_sync_readahead(mapping, ra, filp, index,
+ last_index - index);
+ filemap_get_read_batch(mapping, index, last_index, pvec);
+ }
+ if (!pagevec_count(pvec)) {
+ if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
+ return -EAGAIN;
+ err = filemap_create_page(filp, mapping,
+ iocb->ki_pos >> PAGE_SHIFT, pvec);
+ if (err == AOP_TRUNCATED_PAGE)
+ goto retry;
+ return err;
+ }
- page = generic_file_buffered_read_pagenotuptodate(iocb,
- filp, iter, page, pg_pos, pg_count);
- if (IS_ERR_OR_NULL(page)) {
- for (j = i + 1; j < nr_got; j++)
- put_page(pages[j]);
- nr_got = i;
- err = PTR_ERR_OR_ZERO(page);
- break;
- }
- }
+ page = pvec->pages[pagevec_count(pvec) - 1];
+ if (PageReadahead(page)) {
+ err = filemap_readahead(iocb, filp, mapping, page, last_index);
+ if (err)
+ goto err;
+ }
+ if (!PageUptodate(page)) {
+ if ((iocb->ki_flags & IOCB_WAITQ) && pagevec_count(pvec) > 1)
+ iocb->ki_flags |= IOCB_NOWAIT;
+ err = filemap_update_page(iocb, mapping, iter, page);
+ if (err)
+ goto err;
}
- if (likely(nr_got))
- return nr_got;
- if (err)
- return err;
- /*
- * No pages and no error means we raced and should retry:
- */
- goto find_page;
+ return 0;
+err:
+ if (err < 0)
+ put_page(page);
+ if (likely(--pvec->nr))
+ return 0;
+ if (err == AOP_TRUNCATED_PAGE)
+ goto retry;
+ return err;
}
/**
- * generic_file_buffered_read - generic file read routine
- * @iocb: the iocb to read
- * @iter: data destination
- * @written: already copied
- *
- * This is a generic file read routine, and uses the
- * mapping->a_ops->readpage() function for the actual low-level stuff.
+ * filemap_read - Read data from the page cache.
+ * @iocb: The iocb to read.
+ * @iter: Destination for the data.
+ * @already_read: Number of bytes already read by the caller.
*
- * This is really ugly. But the goto's actually try to clarify some
- * of the logic when it comes to error handling etc.
+ * Copies data from the page cache. If the data is not currently present,
+ * uses the readahead and readpage address_space operations to fetch it.
*
- * Return:
- * * total number of bytes copied, including those the were already @written
- * * negative error code if nothing was copied
+ * Return: Total number of bytes copied, including those already read by
+ * the caller. If an error happens before any bytes are copied, returns
+ * a negative error number.
*/
-ssize_t generic_file_buffered_read(struct kiocb *iocb,
- struct iov_iter *iter, ssize_t written)
+ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
+ ssize_t already_read)
{
struct file *filp = iocb->ki_filp;
struct file_ra_state *ra = &filp->f_ra;
struct address_space *mapping = filp->f_mapping;
struct inode *inode = mapping->host;
- struct page *pages_onstack[PAGEVEC_SIZE], **pages = NULL;
- unsigned int nr_pages = min_t(unsigned int, 512,
- ((iocb->ki_pos + iter->count + PAGE_SIZE - 1) >> PAGE_SHIFT) -
- (iocb->ki_pos >> PAGE_SHIFT));
- int i, pg_nr, error = 0;
+ struct pagevec pvec;
+ int i, error = 0;
bool writably_mapped;
loff_t isize, end_offset;
return 0;
iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
-
- if (nr_pages > ARRAY_SIZE(pages_onstack))
- pages = kmalloc_array(nr_pages, sizeof(void *), GFP_KERNEL);
-
- if (!pages) {
- pages = pages_onstack;
- nr_pages = min_t(unsigned int, nr_pages, ARRAY_SIZE(pages_onstack));
- }
+ pagevec_init(&pvec);
do {
cond_resched();
* can no longer safely return -EIOCBQUEUED. Hence mark
* an async read NOWAIT at that point.
*/
- if ((iocb->ki_flags & IOCB_WAITQ) && written)
+ if ((iocb->ki_flags & IOCB_WAITQ) && already_read)
iocb->ki_flags |= IOCB_NOWAIT;
- i = 0;
- pg_nr = generic_file_buffered_read_get_pages(iocb, iter,
- pages, nr_pages);
- if (pg_nr < 0) {
- error = pg_nr;
+ error = filemap_get_pages(iocb, iter, &pvec);
+ if (error < 0)
break;
- }
/*
* i_size must be checked after we know the pages are Uptodate.
isize = i_size_read(inode);
if (unlikely(iocb->ki_pos >= isize))
goto put_pages;
-
end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count);
- while ((iocb->ki_pos >> PAGE_SHIFT) + pg_nr >
- (end_offset + PAGE_SIZE - 1) >> PAGE_SHIFT)
- put_page(pages[--pg_nr]);
-
/*
* Once we start copying data, we don't want to be touching any
* cachelines that might be contended:
*/
if (iocb->ki_pos >> PAGE_SHIFT !=
ra->prev_pos >> PAGE_SHIFT)
- mark_page_accessed(pages[0]);
- for (i = 1; i < pg_nr; i++)
- mark_page_accessed(pages[i]);
+ mark_page_accessed(pvec.pages[0]);
- for (i = 0; i < pg_nr; i++) {
- unsigned int offset = iocb->ki_pos & ~PAGE_MASK;
- unsigned int bytes = min_t(loff_t, end_offset - iocb->ki_pos,
- PAGE_SIZE - offset);
- unsigned int copied;
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+ size_t page_size = thp_size(page);
+ size_t offset = iocb->ki_pos & (page_size - 1);
+ size_t bytes = min_t(loff_t, end_offset - iocb->ki_pos,
+ page_size - offset);
+ size_t copied;
+ if (end_offset < page_offset(page))
+ break;
+ if (i > 0)
+ mark_page_accessed(page);
/*
* 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 (writably_mapped)
- flush_dcache_page(pages[i]);
+ if (writably_mapped) {
+ int j;
+
+ for (j = 0; j < thp_nr_pages(page); j++)
+ flush_dcache_page(page + j);
+ }
- copied = copy_page_to_iter(pages[i], offset, bytes, iter);
+ copied = copy_page_to_iter(page, offset, bytes, iter);
- written += copied;
+ already_read += copied;
iocb->ki_pos += copied;
ra->prev_pos = iocb->ki_pos;
}
}
put_pages:
- for (i = 0; i < pg_nr; i++)
- put_page(pages[i]);
+ for (i = 0; i < pagevec_count(&pvec); i++)
+ put_page(pvec.pages[i]);
+ pagevec_reinit(&pvec);
} while (iov_iter_count(iter) && iocb->ki_pos < isize && !error);
file_accessed(filp);
- if (pages != pages_onstack)
- kfree(pages);
-
- return written ? written : error;
+ return already_read ? already_read : error;
}
-EXPORT_SYMBOL_GPL(generic_file_buffered_read);
+EXPORT_SYMBOL_GPL(filemap_read);
/**
* generic_file_read_iter - generic filesystem read routine
ssize_t retval = 0;
if (!count)
- goto out; /* skip atime */
+ return 0; /* skip atime */
if (iocb->ki_flags & IOCB_DIRECT) {
struct file *file = iocb->ki_filp;
iocb->ki_pos,
iocb->ki_pos + count - 1);
if (retval < 0)
- goto out;
+ return retval;
}
file_accessed(file);
iocb->ki_pos += retval;
count -= retval;
}
- iov_iter_revert(iter, count - iov_iter_count(iter));
+ if (retval != -EIOCBQUEUED)
+ iov_iter_revert(iter, count - iov_iter_count(iter));
/*
* Btrfs can have a short DIO read if we encounter
*/
if (retval < 0 || !count || iocb->ki_pos >= size ||
IS_DAX(inode))
- goto out;
+ return retval;
}
- retval = generic_file_buffered_read(iocb, iter, retval);
-out:
- return retval;
+ return filemap_read(iocb, iter, retval);
}
EXPORT_SYMBOL(generic_file_read_iter);
+static inline loff_t page_seek_hole_data(struct xa_state *xas,
+ struct address_space *mapping, struct page *page,
+ loff_t start, loff_t end, bool seek_data)
+{
+ const struct address_space_operations *ops = mapping->a_ops;
+ size_t offset, bsz = i_blocksize(mapping->host);
+
+ if (xa_is_value(page) || PageUptodate(page))
+ return seek_data ? start : end;
+ if (!ops->is_partially_uptodate)
+ return seek_data ? end : start;
+
+ xas_pause(xas);
+ rcu_read_unlock();
+ lock_page(page);
+ if (unlikely(page->mapping != mapping))
+ goto unlock;
+
+ offset = offset_in_thp(page, start) & ~(bsz - 1);
+
+ do {
+ if (ops->is_partially_uptodate(page, offset, bsz) == seek_data)
+ break;
+ start = (start + bsz) & ~(bsz - 1);
+ offset += bsz;
+ } while (offset < thp_size(page));
+unlock:
+ unlock_page(page);
+ rcu_read_lock();
+ return start;
+}
+
+static inline
+unsigned int seek_page_size(struct xa_state *xas, struct page *page)
+{
+ if (xa_is_value(page))
+ return PAGE_SIZE << xa_get_order(xas->xa, xas->xa_index);
+ return thp_size(page);
+}
+
+/**
+ * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache.
+ * @mapping: Address space to search.
+ * @start: First byte to consider.
+ * @end: Limit of search (exclusive).
+ * @whence: Either SEEK_HOLE or SEEK_DATA.
+ *
+ * If the page cache knows which blocks contain holes and which blocks
+ * contain data, your filesystem can use this function to implement
+ * SEEK_HOLE and SEEK_DATA. This is useful for filesystems which are
+ * entirely memory-based such as tmpfs, and filesystems which support
+ * unwritten extents.
+ *
+ * Return: The requested offset on successs, or -ENXIO if @whence specifies
+ * SEEK_DATA and there is no data after @start. There is an implicit hole
+ * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start
+ * and @end contain data.
+ */
+loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
+ loff_t end, int whence)
+{
+ XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT);
+ pgoff_t max = (end - 1) / PAGE_SIZE;
+ bool seek_data = (whence == SEEK_DATA);
+ struct page *page;
+
+ if (end <= start)
+ return -ENXIO;
+
+ rcu_read_lock();
+ while ((page = find_get_entry(&xas, max, XA_PRESENT))) {
+ loff_t pos = xas.xa_index * PAGE_SIZE;
+
+ if (start < pos) {
+ if (!seek_data)
+ goto unlock;
+ start = pos;
+ }
+
+ pos += seek_page_size(&xas, page);
+ start = page_seek_hole_data(&xas, mapping, page, start, pos,
+ seek_data);
+ if (start < pos)
+ goto unlock;
+ if (!xa_is_value(page))
+ put_page(page);
+ }
+ rcu_read_unlock();
+
+ if (seek_data)
+ return -ENXIO;
+ goto out;
+
+unlock:
+ rcu_read_unlock();
+ if (!xa_is_value(page))
+ put_page(page);
+out:
+ if (start > end)
+ return end;
+ return start;
+}
+
#ifdef CONFIG_MMU
#define MMAP_LOTSAMISS (100)
/*
}
iocb->ki_pos = pos;
}
- iov_iter_revert(from, write_len - iov_iter_count(from));
+ if (written != -EIOCBQUEUED)
+ iov_iter_revert(from, write_len - iov_iter_count(from));
out:
return written;
}
projects / linux-2.6-microblaze.git / blobdiff