btrfs: convert from readpages to readahead

Implement the new readahead method in btrfs using the new
readahead_page_batch() function.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Gao Xiang <gaoxiang25@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Link: http://lkml.kernel.org/r/20200414150233.24495-18-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 39e45b8..fc46adf 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4367,51 +4367,32 @@ int extent_writepages(struct address_space *mapping,
        return ret;
 }
 
-int extent_readpages(struct address_space *mapping, struct list_head *pages,
-                    unsigned nr_pages)
+void extent_readahead(struct readahead_control *rac)
 {
        struct bio *bio = NULL;
        unsigned long bio_flags = 0;
        struct page *pagepool[16];
        struct extent_map *em_cached = NULL;
-       int nr = 0;
        u64 prev_em_start = (u64)-1;
+       int nr;
 
-       while (!list_empty(pages)) {
-               u64 contig_end = 0;
-
-               for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) {
-                       struct page *page = lru_to_page(pages);
-
-                       prefetchw(&page->flags);
-                       list_del(&page->lru);
-                       if (add_to_page_cache_lru(page, mapping, page->index,
-                                               readahead_gfp_mask(mapping))) {
-                               put_page(page);
-                               break;
-                       }
-
-                       pagepool[nr++] = page;
-                       contig_end = page_offset(page) + PAGE_SIZE - 1;
-               }
-
-               if (nr) {
-                       u64 contig_start = page_offset(pagepool[0]);
+       while ((nr = readahead_page_batch(rac, pagepool))) {
+               u64 contig_start = page_offset(pagepool[0]);
+               u64 contig_end = page_offset(pagepool[nr - 1]) + PAGE_SIZE - 1;
 
-                       ASSERT(contig_start + nr * PAGE_SIZE - 1 == contig_end);
+               ASSERT(contig_start + nr * PAGE_SIZE - 1 == contig_end);
 
-                       contiguous_readpages(pagepool, nr, contig_start,
-                                    contig_end, &em_cached, &bio, &bio_flags,
-                                    &prev_em_start);
-               }
+               contiguous_readpages(pagepool, nr, contig_start, contig_end,
+                               &em_cached, &bio, &bio_flags, &prev_em_start);
        }
 
        if (em_cached)
                free_extent_map(em_cached);
 
-       if (bio)
-               return submit_one_bio(bio, 0, bio_flags);
-       return 0;
+       if (bio) {
+               if (submit_one_bio(bio, 0, bio_flags))
+                       return;
+       }
 }
 
 /*

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 2ed65bd..25594e0 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -198,8 +198,7 @@ int extent_writepages(struct address_space *mapping,
                      struct writeback_control *wbc);
 int btree_write_cache_pages(struct address_space *mapping,
                            struct writeback_control *wbc);
-int extent_readpages(struct address_space *mapping, struct list_head *pages,
-                    unsigned nr_pages);
+void extent_readahead(struct readahead_control *rac);
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                __u64 start, __u64 len);
 void set_page_extent_mapped(struct page *page);

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 320d106..ba0aa8b 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4856,8 +4856,8 @@ static void evict_inode_truncate_pages(struct inode *inode)
 
        /*
         * Keep looping until we have no more ranges in the io tree.
-        * We can have ongoing bios started by readpages (called from readahead)
-        * that have their endio callback (extent_io.c:end_bio_extent_readpage)
+        * We can have ongoing bios started by readahead that have
+        * their endio callback (extent_io.c:end_bio_extent_readpage)
         * still in progress (unlocked the pages in the bio but did not yet
         * unlocked the ranges in the io tree). Therefore this means some
         * ranges can still be locked and eviction started because before
@@ -7050,11 +7050,11 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
                         * for it to complete) and then invalidate the pages for
                         * this range (through invalidate_inode_pages2_range()),
                         * but that can lead us to a deadlock with a concurrent
-                        * call to readpages() (a buffered read or a defrag call
+                        * call to readahead (a buffered read or a defrag call
                         * triggered a readahead) on a page lock due to an
                         * ordered dio extent we created before but did not have
                         * yet a corresponding bio submitted (whence it can not
-                        * complete), which makes readpages() wait for that
+                        * complete), which makes readahead wait for that
                         * ordered extent to complete while holding a lock on
                         * that page.
                         */
@@ -8293,11 +8293,9 @@ static int btrfs_writepages(struct address_space *mapping,
        return extent_writepages(mapping, wbc);
 }
 
-static int
-btrfs_readpages(struct file *file, struct address_space *mapping,
-               struct list_head *pages, unsigned nr_pages)
+static void btrfs_readahead(struct readahead_control *rac)
 {
-       return extent_readpages(mapping, pages, nr_pages);
+       extent_readahead(rac);
 }
 
 static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
@@ -10553,7 +10551,7 @@ static const struct address_space_operations btrfs_aops = {
        .readpage       = btrfs_readpage,
        .writepage      = btrfs_writepage,
        .writepages     = btrfs_writepages,
-       .readpages      = btrfs_readpages,
+       .readahead      = btrfs_readahead,
        .direct_IO      = btrfs_direct_IO,
        .invalidatepage = btrfs_invalidatepage,
        .releasepage    = btrfs_releasepage,