mm/filemap: convert filemap_get_pages to take a pagevec

Using a pagevec lets us keep the pages and the number of pages together
which simplifies a lot of the calling conventions.

Link: https://lkml.kernel.org/r/20210122160140.223228-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index f621a7de58331384d04749211a7b80055120e671..aadf9bd340a4965b9f7d439a3a554b304dd3b3c8 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2325,22 +2325,22 @@ static struct page *filemap_create_page(struct kiocb *iocb,
 }
 
 static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
-               struct page **pages, unsigned int nr)
+               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;
+       unsigned int nr = min_t(unsigned long, last_index - index, PAGEVEC_SIZE);
+       int i, j, err = 0;
 
-       nr = min_t(unsigned long, last_index - index, nr);
 find_page:
        if (fatal_signal_pending(current))
                return -EINTR;
 
-       nr_got = find_get_pages_contig(mapping, index, nr, pages);
-       if (nr_got)
+       pvec->nr = find_get_pages_contig(mapping, index, nr, pvec->pages);
+       if (pvec->nr)
                goto got_pages;
 
        if (iocb->ki_flags & IOCB_NOIO)
@@ -2348,17 +2348,17 @@ find_page:
 
        page_cache_sync_readahead(mapping, ra, filp, index, last_index - index);
 
-       nr_got = find_get_pages_contig(mapping, index, nr, pages);
-       if (nr_got)
+       pvec->nr = find_get_pages_contig(mapping, index, nr, pvec->pages);
+       if (pvec->nr)
                goto got_pages;
 
-       pages[0] = filemap_create_page(iocb, iter);
-       err = PTR_ERR_OR_ZERO(pages[0]);
-       if (!IS_ERR_OR_NULL(pages[0]))
-               nr_got = 1;
+       pvec->pages[0] = filemap_create_page(iocb, iter);
+       err = PTR_ERR_OR_ZERO(pvec->pages[0]);
+       if (!IS_ERR_OR_NULL(pvec->pages[0]))
+               pvec->nr = 1;
 got_pages:
-       for (i = 0; i < nr_got; i++) {
-               struct page *page = pages[i];
+       for (i = 0; i < pvec->nr; i++) {
+               struct page *page = pvec->pages[i];
                pgoff_t pg_index = index + i;
                loff_t pg_pos = max(iocb->ki_pos,
                                    (loff_t) pg_index << PAGE_SHIFT);
@@ -2366,9 +2366,9 @@ got_pages:
 
                if (PageReadahead(page)) {
                        if (iocb->ki_flags & IOCB_NOIO) {
-                               for (j = i; j < nr_got; j++)
-                                       put_page(pages[j]);
-                               nr_got = i;
+                               for (j = i; j < pvec->nr; j++)
+                                       put_page(pvec->pages[j]);
+                               pvec->nr = i;
                                err = -EAGAIN;
                                break;
                        }
@@ -2379,9 +2379,9 @@ got_pages:
                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;
+                               for (j = i; j < pvec->nr; j++)
+                                       put_page(pvec->pages[j]);
+                               pvec->nr = i;
                                err = -EAGAIN;
                                break;
                        }
@@ -2389,17 +2389,17 @@ got_pages:
                        page = filemap_update_page(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;
+                               for (j = i + 1; j < pvec->nr; j++)
+                                       put_page(pvec->pages[j]);
+                               pvec->nr = i;
                                err = PTR_ERR_OR_ZERO(page);
                                break;
                        }
                }
        }
 
-       if (likely(nr_got))
-               return nr_got;
+       if (likely(pvec->nr))
+               return 0;
        if (err)
                return err;
        /*
@@ -2431,11 +2431,8 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
        struct file_ra_state *ra = &filp->f_ra;
        struct address_space *mapping = filp->f_mapping;
        struct inode *inode = mapping->host;
-       struct page *pages[PAGEVEC_SIZE];
-       unsigned int nr_pages = min_t(unsigned int, PAGEVEC_SIZE,
-                       ((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;
 
@@ -2457,12 +2454,9 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
                if ((iocb->ki_flags & IOCB_WAITQ) && written)
                        iocb->ki_flags |= IOCB_NOWAIT;
 
-               i = 0;
-               pg_nr = filemap_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.
@@ -2478,9 +2472,9 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
 
                end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count);
 
-               while ((iocb->ki_pos >> PAGE_SHIFT) + pg_nr >
+               while ((iocb->ki_pos >> PAGE_SHIFT) + pvec.nr >
                       (end_offset + PAGE_SIZE - 1) >> PAGE_SHIFT)
-                       put_page(pages[--pg_nr]);
+                       put_page(pvec.pages[--pvec.nr]);
 
                /*
                 * Once we start copying data, we don't want to be touching any
@@ -2494,11 +2488,11 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
                 */
                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 = 1; i < pagevec_count(&pvec); i++)
+                       mark_page_accessed(pvec.pages[i]);
 
-               for (i = 0; i < pg_nr; i++) {
+               for (i = 0; i < pagevec_count(&pvec); i++) {
                        unsigned int offset = iocb->ki_pos & ~PAGE_MASK;
                        unsigned int bytes = min_t(loff_t, end_offset - iocb->ki_pos,
                                                   PAGE_SIZE - offset);
@@ -2510,9 +2504,9 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
                         * before reading the page on the kernel side.
                         */
                        if (writably_mapped)
-                               flush_dcache_page(pages[i]);
+                               flush_dcache_page(pvec.pages[i]);
 
-                       copied = copy_page_to_iter(pages[i], offset, bytes, iter);
+                       copied = copy_page_to_iter(pvec.pages[i], offset, bytes, iter);
 
                        written += copied;
                        iocb->ki_pos += copied;
@@ -2524,8 +2518,8 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
                        }
                }
 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]);
        } while (iov_iter_count(iter) && iocb->ki_pos < isize && !error);
 
        file_accessed(filp);