* 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;
}
/*
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);
-
- if (unlikely(error)) {
- put_page(page);
- return error != AOP_TRUNCATED_PAGE ? ERR_PTR(error) : NULL;
- }
+ error = mapping->a_ops->readpage(file, page);
+ if (error)
+ return error;
+ if (PageUptodate(page))
+ return 0;
+ error = lock_page_killable(page);
+ if (error)
+ return error;
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);
+ if (page->mapping == NULL) {
+ /* page truncated */
+ error = AOP_TRUNCATED_PAGE;
+ } else {
+ shrink_readahead_size_eio(&file->f_ra);
+ error = -EIO;
}
- unlock_page(page);
}
-
- return page;
+ unlock_page(page);
+ return error;
}
-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 bool filemap_range_uptodate(struct address_space *mapping,
+ loff_t pos, struct iov_iter *iter, struct page *page)
{
- struct address_space *mapping = filp->f_mapping;
- struct inode *inode = mapping->host;
- int error;
+ int count;
- /*
- * 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 (PageUptodate(page))
- return page;
-
- if (inode->i_blkbits == PAGE_SHIFT ||
- !mapping->a_ops->is_partially_uptodate)
- goto page_not_up_to_date;
+ return true;
/* 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;
+ 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;
-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);
+ count = iter->count;
+ if (page_offset(page) > pos) {
+ count -= page_offset(page) - pos;
+ pos = 0;
+ } else {
+ pos -= page_offset(page);
}
-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;
- }
+ return mapping->a_ops->is_partially_uptodate(page, pos, count);
+}
- /* Did somebody else fill it already? */
- if (PageUptodate(page)) {
- unlock_page(page);
- return page;
+static int filemap_update_page(struct kiocb *iocb,
+ struct address_space *mapping, struct iov_iter *iter,
+ struct page *page)
+{
+ int 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;
}
- return generic_file_buffered_read_readpage(iocb, filp, mapping, page);
+ if (!page->mapping)
+ goto truncated;
+
+ error = 0;
+ if (filemap_range_uptodate(mapping, iocb->ki_pos, iter, page))
+ goto unlock;
+
+ error = -EAGAIN;
+ if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
+ goto unlock;
+
+ 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;
- return generic_file_buffered_read_readpage(iocb, filp, mapping, page);
+ error = filemap_read_page(file, mapping, page);
+ if (error)
+ goto error;
+
+ pagevec_add(pvec, page);
+ return 0;
+error:
+ put_page(page);
+ return error;
}
-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;
+ int err = 0;
- nr = min_t(unsigned long, last_index - index, nr);
+ last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE);
find_page:
if (fatal_signal_pending(current))
return -EINTR;
- nr_got = find_get_pages_contig(mapping, index, nr, pages);
- if (nr_got)
+ filemap_get_read_batch(mapping, index, last_index, pvec);
+ if (pvec->nr)
goto got_pages;
if (iocb->ki_flags & IOCB_NOIO)
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;
+ 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 find_page;
+ return err;
+ }
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;
+ {
+ struct page *page = pvec->pages[pvec->nr - 1];
+ pgoff_t pg_index = page->index;
if (PageReadahead(page)) {
if (iocb->ki_flags & IOCB_NOIO) {
- for (j = i; j < nr_got; j++)
- put_page(pages[j]);
- nr_got = i;
+ put_page(page);
+ pvec->nr--;
err = -EAGAIN;
- break;
+ goto err;
}
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;
- }
-
- 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;
+ 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) {
+ if (err < 0)
+ put_page(page);
+ pvec->nr--;
}
}
}
- if (likely(nr_got))
- return nr_got;
+err:
+ if (likely(pvec->nr))
+ return 0;
+ if (err == AOP_TRUNCATED_PAGE)
+ goto find_page;
if (err)
return err;
/*
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();
if ((iocb->ki_flags & IOCB_WAITQ) && written)
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;
- copied = copy_page_to_iter(pages[i], offset, bytes, iter);
+ for (j = 0; j < thp_nr_pages(page); j++)
+ flush_dcache_page(page + j);
+ }
+
+ copied = copy_page_to_iter(page, offset, bytes, iter);
written += copied;
iocb->ki_pos += copied;
}
}
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;
}
EXPORT_SYMBOL_GPL(generic_file_buffered_read);
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
}
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