md/bitmap: centralise allocation of bitmap file pages.

Instead of allocating pages in read_sb_page, read_page and
bitmap_read_sb, allocate them all in bitmap_init_from disk.

Also replace the hack of calling "attach_page_buffers(page, NULL)" to
ensure that free_buffer() won't complain, by putting a test for
PagePrivate in free_buffer().

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index c042efd..324a198 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -130,22 +130,14 @@ static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
  */
 
 /* IO operations when bitmap is stored near all superblocks */
-static struct page *read_sb_page(struct mddev *mddev, loff_t offset,
-                                struct page *page,
-                                unsigned long index, int size)
+static int read_sb_page(struct mddev *mddev, loff_t offset,
+                       struct page *page,
+                       unsigned long index, int size)
 {
        /* choose a good rdev and read the page from there */
 
        struct md_rdev *rdev;
        sector_t target;
-       int did_alloc = 0;
-
-       if (!page) {
-               page = alloc_page(GFP_KERNEL);
-               if (!page)
-                       return ERR_PTR(-ENOMEM);
-               did_alloc = 1;
-       }
 
        rdev_for_each(rdev, mddev) {
                if (! test_bit(In_sync, &rdev->flags)
@@ -158,15 +150,10 @@ static struct page *read_sb_page(struct mddev *mddev, loff_t offset,
                                 roundup(size, bdev_logical_block_size(rdev->bdev)),
                                 page, READ, true)) {
                        page->index = index;
-                       attach_page_buffers(page, NULL); /* so that free_buffer will
-                                                         * quietly no-op */
-                       return page;
+                       return 0;
                }
        }
-       if (did_alloc)
-               put_page(page);
-       return ERR_PTR(-EIO);
-
+       return -EIO;
 }
 
 static struct md_rdev *next_active_rdev(struct md_rdev *rdev, struct mddev *mddev)
@@ -325,8 +312,12 @@ __clear_page_buffers(struct page *page)
 }
 static void free_buffers(struct page *page)
 {
-       struct buffer_head *bh = page_buffers(page);
+       struct buffer_head *bh;
 
+       if (!PagePrivate(page))
+               return;
+
+       bh = page_buffers(page);
        while (bh) {
                struct buffer_head *next = bh->b_this_page;
                free_buffer_head(bh);
@@ -343,11 +334,12 @@ static void free_buffers(struct page *page)
  * This usage is similar to how swap files are handled, and allows us
  * to write to a file with no concerns of memory allocation failing.
  */
-static struct page *read_page(struct file *file, unsigned long index,
-                             struct bitmap *bitmap,
-                             unsigned long count)
+static int read_page(struct file *file, unsigned long index,
+                    struct bitmap *bitmap,
+                    unsigned long count,
+                    struct page *page)
 {
-       struct page *page = NULL;
+       int ret = 0;
        struct inode *inode = file->f_path.dentry->d_inode;
        struct buffer_head *bh;
        sector_t block;
@@ -355,16 +347,9 @@ static struct page *read_page(struct file *file, unsigned long index,
        pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
                 (unsigned long long)index << PAGE_SHIFT);
 
-       page = alloc_page(GFP_KERNEL);
-       if (!page)
-               page = ERR_PTR(-ENOMEM);
-       if (IS_ERR(page))
-               goto out;
-
        bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
        if (!bh) {
-               put_page(page);
-               page = ERR_PTR(-ENOMEM);
+               ret = -ENOMEM;
                goto out;
        }
        attach_page_buffers(page, bh);
@@ -376,8 +361,7 @@ static struct page *read_page(struct file *file, unsigned long index,
                        bh->b_blocknr = bmap(inode, block);
                        if (bh->b_blocknr == 0) {
                                /* Cannot use this file! */
-                               free_buffers(page);
-                               page = ERR_PTR(-EINVAL);
+                               ret = -EINVAL;
                                goto out;
                        }
                        bh->b_bdev = inode->i_sb->s_bdev;
@@ -400,17 +384,15 @@ static struct page *read_page(struct file *file, unsigned long index,
 
        wait_event(bitmap->write_wait,
                   atomic_read(&bitmap->pending_writes)==0);
-       if (bitmap->flags & BITMAP_WRITE_ERROR) {
-               free_buffers(page);
-               page = ERR_PTR(-EIO);
-       }
+       if (bitmap->flags & BITMAP_WRITE_ERROR)
+               ret = -EIO;
 out:
-       if (IS_ERR(page))
-               printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %ld\n",
+       if (ret)
+               printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %d\n",
                        (int)PAGE_SIZE,
                        (unsigned long long)index << PAGE_SHIFT,
-                       PTR_ERR(page));
-       return page;
+                       ret);
+       return ret;
 }
 
 /*
@@ -552,6 +534,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
        unsigned long chunksize, daemon_sleep, write_behind;
        unsigned long long events;
        int err = -EINVAL;
+       struct page *sb_page;
 
        if (!bitmap->file && !bitmap->mddev->bitmap_info.offset) {
                chunksize = 128 * 1024 * 1024;
@@ -562,24 +545,27 @@ static int bitmap_read_sb(struct bitmap *bitmap)
                goto out_no_sb;
        }
        /* page 0 is the superblock, read it... */
+       sb_page = alloc_page(GFP_KERNEL);
+       if (!sb_page)
+               return -ENOMEM;
+       bitmap->sb_page = sb_page;
+
        if (bitmap->file) {
                loff_t isize = i_size_read(bitmap->file->f_mapping->host);
                int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
 
-               bitmap->sb_page = read_page(bitmap->file, 0, bitmap, bytes);
+               err = read_page(bitmap->file, 0,
+                               bitmap, bytes, sb_page);
        } else {
-               bitmap->sb_page = read_sb_page(bitmap->mddev,
-                                              bitmap->mddev->bitmap_info.offset,
-                                              NULL,
-                                              0, sizeof(bitmap_super_t));
+               err = read_sb_page(bitmap->mddev,
+                                  bitmap->mddev->bitmap_info.offset,
+                                  sb_page,
+                                  0, sizeof(bitmap_super_t));
        }
-       if (IS_ERR(bitmap->sb_page)) {
-               err = PTR_ERR(bitmap->sb_page);
-               bitmap->sb_page = NULL;
+       if (err)
                return err;
-       }
 
-       sb = kmap_atomic(bitmap->sb_page);
+       sb = kmap_atomic(sb_page);
 
        chunksize = le32_to_cpu(sb->chunksize);
        daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
@@ -948,7 +934,8 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int n
 static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 {
        unsigned long i, chunks, index, oldindex, bit;
-       struct page *page = NULL, *oldpage = NULL;
+       int pnum;
+       struct page *page = NULL;
        unsigned long num_pages, bit_cnt = 0;
        struct file *file;
        unsigned long bytes, offset;
@@ -999,6 +986,22 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
        if (!bitmap->filemap)
                goto err;
 
+       pnum = 0;
+       offset = 0;
+       if (bitmap->sb_page) {
+               bitmap->filemap[0] = bitmap->sb_page;
+               pnum = 1;
+               offset = sizeof(bitmap_super_t);
+       }
+       for ( ; pnum < num_pages; pnum++) {
+               bitmap->filemap[pnum] = alloc_page(GFP_KERNEL);
+               if (!bitmap->filemap[pnum]) {
+                       bitmap->file_pages = pnum;
+                       goto err;
+               }
+       }
+       bitmap->file_pages = pnum;
+
        /* We need 4 bits per page, rounded up to a multiple of sizeof(unsigned long) */
        bitmap->filemap_attr = kzalloc(
                roundup(DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
@@ -1019,39 +1022,22 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                                count = bytes - index * PAGE_SIZE;
                        else
                                count = PAGE_SIZE;
-                       if (index == 0 && bitmap->sb_page) {
-                               /*
-                                * if we're here then the superblock page
-                                * contains some bits (PAGE_SIZE != sizeof sb)
-                                * we've already read it in, so just use it
-                                */
-                               page = bitmap->sb_page;
-                               offset = sizeof(bitmap_super_t);
-                               if (!file)
-                                       page = read_sb_page(
-                                               bitmap->mddev,
-                                               bitmap->mddev->bitmap_info.offset,
-                                               page,
-                                               index, count);
-                       } else if (file) {
-                               page = read_page(file, index, bitmap, count);
-                               offset = 0;
-                       } else {
-                               page = read_sb_page(bitmap->mddev,
-                                                   bitmap->mddev->bitmap_info.offset,
-                                                   NULL,
-                                                   index, count);
-                               offset = 0;
-                       }
-                       if (IS_ERR(page)) { /* read error */
-                               ret = PTR_ERR(page);
+                       page = bitmap->filemap[index];
+                       if (file)
+                               ret = read_page(file, index, bitmap,
+                                               count, page);
+                       else
+                               ret = read_sb_page(
+                                       bitmap->mddev,
+                                       bitmap->mddev->bitmap_info.offset,
+                                       page,
+                                       index, count);
+
+                       if (ret)
                                goto err;
-                       }
 
                        oldindex = index;
-                       oldpage = page;
 
-                       bitmap->filemap[bitmap->file_pages++] = page;
                        bitmap->last_page_size = count;
 
                        if (outofdate) {
@@ -1085,6 +1071,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
                                               needed);
                        bit_cnt++;
                }
+               offset = 0;
        }
 
        printk(KERN_INFO "%s: bitmap initialized from disk: "