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Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c76
1 files changed, 63 insertions, 13 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 6f1be573a5e6..aea58e983a73 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -376,6 +376,38 @@ int filemap_flush(struct address_space *mapping)
}
EXPORT_SYMBOL(filemap_flush);
+/**
+ * filemap_range_has_page - check if a page exists in range.
+ * @mapping: address space within which to check
+ * @start_byte: offset in bytes where the range starts
+ * @end_byte: offset in bytes where the range ends (inclusive)
+ *
+ * Find at least one page in the range supplied, usually used to check if
+ * direct writing in this range will trigger a writeback.
+ */
+bool filemap_range_has_page(struct address_space *mapping,
+ loff_t start_byte, loff_t end_byte)
+{
+ pgoff_t index = start_byte >> PAGE_SHIFT;
+ pgoff_t end = end_byte >> PAGE_SHIFT;
+ struct pagevec pvec;
+ bool ret;
+
+ if (end_byte < start_byte)
+ return false;
+
+ if (mapping->nrpages == 0)
+ return false;
+
+ pagevec_init(&pvec, 0);
+ if (!pagevec_lookup(&pvec, mapping, index, 1))
+ return false;
+ ret = (pvec.pages[0]->index <= end);
+ pagevec_release(&pvec);
+ return ret;
+}
+EXPORT_SYMBOL(filemap_range_has_page);
+
static int __filemap_fdatawait_range(struct address_space *mapping,
loff_t start_byte, loff_t end_byte)
{
@@ -768,10 +800,10 @@ struct wait_page_key {
struct wait_page_queue {
struct page *page;
int bit_nr;
- wait_queue_t wait;
+ wait_queue_entry_t wait;
};
-static int wake_page_function(wait_queue_t *wait, unsigned mode, int sync, void *arg)
+static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
{
struct wait_page_key *key = arg;
struct wait_page_queue *wait_page
@@ -834,7 +866,7 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
struct page *page, int bit_nr, int state, bool lock)
{
struct wait_page_queue wait_page;
- wait_queue_t *wait = &wait_page.wait;
+ wait_queue_entry_t *wait = &wait_page.wait;
int ret = 0;
init_wait(wait);
@@ -845,9 +877,9 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
for (;;) {
spin_lock_irq(&q->lock);
- if (likely(list_empty(&wait->task_list))) {
+ if (likely(list_empty(&wait->entry))) {
if (lock)
- __add_wait_queue_tail_exclusive(q, wait);
+ __add_wait_queue_entry_tail_exclusive(q, wait);
else
__add_wait_queue(q, wait);
SetPageWaiters(page);
@@ -907,7 +939,7 @@ int wait_on_page_bit_killable(struct page *page, int bit_nr)
*
* Add an arbitrary @waiter to the wait queue for the nominated @page.
*/
-void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
+void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter)
{
wait_queue_head_t *q = page_waitqueue(page);
unsigned long flags;
@@ -2038,10 +2070,17 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
loff_t size;
size = i_size_read(inode);
- retval = filemap_write_and_wait_range(mapping, iocb->ki_pos,
- iocb->ki_pos + count - 1);
- if (retval < 0)
- goto out;
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ if (filemap_range_has_page(mapping, iocb->ki_pos,
+ iocb->ki_pos + count - 1))
+ return -EAGAIN;
+ } else {
+ retval = filemap_write_and_wait_range(mapping,
+ iocb->ki_pos,
+ iocb->ki_pos + count - 1);
+ if (retval < 0)
+ goto out;
+ }
file_accessed(file);
@@ -2642,6 +2681,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
pos = iocb->ki_pos;
+ if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
+ return -EINVAL;
+
if (limit != RLIM_INFINITY) {
if (iocb->ki_pos >= limit) {
send_sig(SIGXFSZ, current, 0);
@@ -2710,9 +2752,17 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
write_len = iov_iter_count(from);
end = (pos + write_len - 1) >> PAGE_SHIFT;
- written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
- if (written)
- goto out;
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ /* If there are pages to writeback, return */
+ if (filemap_range_has_page(inode->i_mapping, pos,
+ pos + iov_iter_count(from)))
+ return -EAGAIN;
+ } else {
+ written = filemap_write_and_wait_range(mapping, pos,
+ pos + write_len - 1);
+ if (written)
+ goto out;
+ }
/*
* After a write we want buffered reads to be sure to go to disk to get