1 files changed, 66 insertions, 25 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index e081558d52ff..f658703c42e6 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1963,18 +1963,27 @@ static inline struct page *extent_buffer_page(struct extent_buffer *eb, int i)
         struct page *p;
         if (i == 0)
                 return eb->first_page;
+
         i += eb->start >> PAGE_CACHE_SHIFT;
+        if (eb->last_page && eb->last_page->index == i)
+                return eb->last_page;
+
         p = find_get_page(eb->first_page->mapping, i);
         page_cache_release(p);
+        eb->last_page = p;
         return p;
 }
 
+static inline unsigned long num_extent_pages(u64 start, u64 len)
+{
+        return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
+                (start >> PAGE_CACHE_SHIFT);
+}
 struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                                           u64 start, unsigned long len,
                                           gfp_t mask)
 {
-        unsigned long num_pages = ((start + len - 1) >> PAGE_CACHE_SHIFT) -
-                                  (start >> PAGE_CACHE_SHIFT) + 1;
+        unsigned long num_pages = num_extent_pages(start, len);
         unsigned long i;
         unsigned long index = start >> PAGE_CACHE_SHIFT;
         struct extent_buffer *eb;
@@ -1986,7 +1995,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
         if (!eb || IS_ERR(eb))
                 return NULL;
 
-        eb->alloc_addr = __builtin_return_address(0);
+        eb->alloc_addr = (unsigned long)__builtin_return_address(0);
         eb->start = start;
         eb->len = len;
         atomic_set(&eb->refs, 1);
@@ -1994,6 +2003,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
         for (i = 0; i < num_pages; i++, index++) {
                 p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
                 if (!p) {
+                        WARN_ON(1);
                         /* make sure the free only frees the pages we've
                          * grabbed a reference on
                          */
@@ -2021,8 +2031,7 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                                          u64 start, unsigned long len,
                                           gfp_t mask)
 {
-        unsigned long num_pages = ((start + len - 1) >> PAGE_CACHE_SHIFT) -
-                                  (start >> PAGE_CACHE_SHIFT) + 1;
+        unsigned long num_pages = num_extent_pages(start, len);
         unsigned long i;
         unsigned long index = start >> PAGE_CACHE_SHIFT;
         struct extent_buffer *eb;
@@ -2033,7 +2042,7 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
         if (!eb || IS_ERR(eb))
                 return NULL;
 
-        eb->alloc_addr = __builtin_return_address(0);
+        eb->alloc_addr = (unsigned long)__builtin_return_address(0);
         eb->start = start;
         eb->len = len;
         atomic_set(&eb->refs, 1);
@@ -2070,8 +2079,7 @@ void free_extent_buffer(struct extent_buffer *eb)
         if (!atomic_dec_and_test(&eb->refs))
                 return;
 
-        num_pages = ((eb->start + eb->len - 1) >> PAGE_CACHE_SHIFT) -
-                (eb->start >> PAGE_CACHE_SHIFT) + 1;
+        num_pages = num_extent_pages(eb->start, eb->len);
 
         if (eb->first_page)
                 page_cache_release(eb->first_page);
@@ -2094,8 +2102,7 @@ int clear_extent_buffer_dirty(struct extent_map_tree *tree,
         u64 end = start + eb->len - 1;
 
         set = clear_extent_dirty(tree, start, end, GFP_NOFS);
-        num_pages = ((eb->start + eb->len - 1) >> PAGE_CACHE_SHIFT) -
-                (eb->start >> PAGE_CACHE_SHIFT) + 1;
+        num_pages = num_extent_pages(eb->start, eb->len);
 
         for (i = 0; i < num_pages; i++) {
                 page = extent_buffer_page(eb, i);
@@ -2145,8 +2152,7 @@ int set_extent_buffer_uptodate(struct extent_map_tree *tree,
         struct page *page;
         unsigned long num_pages;
 
-        num_pages = ((eb->start + eb->len - 1) >> PAGE_CACHE_SHIFT) -
-                (eb->start >> PAGE_CACHE_SHIFT) + 1;
+        num_pages = num_extent_pages(eb->start, eb->len);
 
         set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
                             GFP_NOFS);
@@ -2191,8 +2197,7 @@ int read_extent_buffer_pages(struct extent_map_tree *tree,
                 return 0;
         }
 
-        num_pages = ((eb->start + eb->len - 1) >> PAGE_CACHE_SHIFT) -
-                (eb->start >> PAGE_CACHE_SHIFT) + 1;
+        num_pages = num_extent_pages(eb->start, eb->len);
         for (i = 0; i < num_pages; i++) {
                 page = extent_buffer_page(eb, i);
                 if (PageUptodate(page)) {
@@ -2267,14 +2272,14 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
 }
 EXPORT_SYMBOL(read_extent_buffer);
 
-int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
-                      unsigned long min_len,
-                      char **token, char **map,
-                      unsigned long *map_start,
-                      unsigned long *map_len, int km)
+static int __map_extent_buffer(struct extent_buffer *eb, unsigned long start,
+                               unsigned long min_len, char **token, char **map,
+                               unsigned long *map_start,
+                               unsigned long *map_len, int km)
 {
         size_t offset = start & (PAGE_CACHE_SIZE - 1);
         char *kaddr;
+        struct page *p;
         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
         unsigned long end_i = (start_offset + start + min_len) >>
@@ -2283,21 +2288,59 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
         if (i != end_i)
                 return -EINVAL;
 
-        WARN_ON(start > eb->len);
+        if (start >= eb->len) {
+                printk("bad start in map eb start %Lu len %lu caller start %lu min %lu\n", eb->start, eb->len, start, min_len);
+                WARN_ON(1);
+        }
 
         if (i == 0) {
                 offset = start_offset;
                 *map_start = 0;
         } else {
+                offset = 0;
                 *map_start = (i << PAGE_CACHE_SHIFT) - start_offset;
         }
 
-        kaddr = kmap_atomic(extent_buffer_page(eb, i), km);
+        p = extent_buffer_page(eb, i);
+        WARN_ON(!PageUptodate(p));
+        kaddr = kmap_atomic(p, km);
         *token = kaddr;
         *map = kaddr + offset;
         *map_len = PAGE_CACHE_SIZE - offset;
         return 0;
 }
+
+int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
+                      unsigned long min_len,
+                      char **token, char **map,
+                      unsigned long *map_start,
+                      unsigned long *map_len, int km)
+{
+        int err;
+        int save = 0;
+        if (eb->map_token) {
+                if (start >= eb->map_start &&
+                    start + min_len <= eb->map_start + eb->map_len) {
+                        *token = eb->map_token;
+                        *map = eb->kaddr;
+                        *map_start = eb->map_start;
+                        *map_len = eb->map_len;
+                        return 0;
+                }
+                unmap_extent_buffer(eb, eb->map_token, km);
+                eb->map_token = NULL;
+                save = 1;
+        }
+        err = __map_extent_buffer(eb, start, min_len, token, map,
+                                   map_start, map_len, km);
+        if (!err && save) {
+                eb->map_token = *token;
+                eb->kaddr = *map;
+                eb->map_start = *map_start;
+                eb->map_len = *map_len;
+        }
+        return err;
+}
 EXPORT_SYMBOL(map_extent_buffer);
 
 void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
@@ -2574,7 +2617,6 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
                         ((unsigned long)PAGE_CACHE_SIZE - 1);
                 src_off_in_page = src_end &
                         ((unsigned long)PAGE_CACHE_SIZE - 1);
-
                 if (src_i == 0)
                         src_off_in_page += start_offset;
                 if (dst_i == 0)
@@ -2582,14 +2624,13 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
 
                 cur = min(len, src_off_in_page + 1);
                 cur = min(cur, dst_off_in_page + 1);
-
                 move_pages(extent_buffer_page(dst, dst_i),
                            extent_buffer_page(dst, src_i),
                            dst_off_in_page - cur + 1,
                            src_off_in_page - cur + 1, cur);
 
-                dst_end -= cur - 1;
-                src_end -= cur - 1;
+                dst_end -= cur;
+                src_end -= cur;
                 len -= cur;
         }
 }