2 files changed, 139 insertions, 151 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index e40d3e4..bedd66e 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -67,7 +67,6 @@ static inline char * bmname(struct bitmap *bitmap)
 	return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
 }
 
-#define WRITE_POOL_SIZE 256
 
 /*
  * just a placeholder - calls kmalloc for bitmap pages
@@ -279,75 +278,137 @@ static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wai
  */
 static int write_page(struct bitmap *bitmap, struct page *page, int wait)
 {
-	int ret = -ENOMEM;
+	struct buffer_head *bh;
 
 	if (bitmap->file == NULL)
 		return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
 
-	flush_dcache_page(page); /* make sure visible to anyone reading the file */
+	bh = page_buffers(page);
 
-	if (wait)
-		lock_page(page);
-	else {
-		if (TestSetPageLocked(page))
-			return -EAGAIN; /* already locked */
-		if (PageWriteback(page)) {
-			unlock_page(page);
-			return -EAGAIN;
-		}
+	while (bh && bh->b_blocknr) {
+		atomic_inc(&bitmap->pending_writes);
+		set_buffer_locked(bh);
+		set_buffer_mapped(bh);
+		submit_bh(WRITE, bh);
+		bh = bh->b_this_page;
+	}
+
+	if (wait) {
+		wait_event(bitmap->write_wait,
+			   atomic_read(&bitmap->pending_writes)==0);
+		return (bitmap->flags & BITMAP_WRITE_ERROR) ? -EIO : 0;
 	}
+	return 0;
+}
+
+static void end_bitmap_write(struct buffer_head *bh, int uptodate)
+{
+	struct bitmap *bitmap = bh->b_private;
+	unsigned long flags;
 
-	ret = page->mapping->a_ops->prepare_write(bitmap->file, page, 0, PAGE_SIZE);
-	if (!ret)
-		ret = page->mapping->a_ops->commit_write(bitmap->file, page, 0,
-			PAGE_SIZE);
-	if (ret) {
-		unlock_page(page);
-		return ret;
+	if (!uptodate) {
+		spin_lock_irqsave(&bitmap->lock, flags);
+		bitmap->flags |= BITMAP_WRITE_ERROR;
+		spin_unlock_irqrestore(&bitmap->lock, flags);
 	}
+	if (atomic_dec_and_test(&bitmap->pending_writes))
+		wake_up(&bitmap->write_wait);
+}
 
-	set_page_dirty(page); /* force it to be written out */
+/* copied from buffer.c */
+static void
+__clear_page_buffers(struct page *page)
+{
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+	page_cache_release(page);
+}
+static void free_buffers(struct page *page)
+{
+	struct buffer_head *bh = page_buffers(page);
 
-	if (!wait) {
-		/* add to list to be waited for */
-		struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO);
-		item->page = page;
-		spin_lock(&bitmap->write_lock);
-		list_add(&item->list, &bitmap->complete_pages);
-		spin_unlock(&bitmap->write_lock);
+	while (bh) {
+		struct buffer_head *next = bh->b_this_page;
+		free_buffer_head(bh);
+		bh = next;
 	}
-	return write_one_page(page, wait);
+	__clear_page_buffers(page);
+	put_page(page);
 }
 
-/* read a page from a file, pinning it into cache, and return bytes_read */
+/* read a page from a file.
+ * We both read the page, and attach buffers to the page to record the
+ * address of each block (using bmap).  These addresses will be used
+ * to write the block later, completely bypassing the filesystem.
+ * 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,
-					unsigned long *bytes_read)
+			      struct bitmap *bitmap,
+			      unsigned long count)
 {
-	struct inode *inode = file->f_mapping->host;
 	struct page *page = NULL;
-	loff_t isize = i_size_read(inode);
-	unsigned long end_index = isize >> PAGE_SHIFT;
+	struct inode *inode = file->f_dentry->d_inode;
+	loff_t pos = index << PAGE_SHIFT;
+	int ret;
+	struct buffer_head *bh;
+	sector_t block;
+	mm_segment_t oldfs;
 
 	PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
 			(unsigned long long)index << PAGE_SHIFT);
 
-	page = read_cache_page(inode->i_mapping, index,
-			(filler_t *)inode->i_mapping->a_ops->readpage, file);
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		page = ERR_PTR(-ENOMEM);
 	if (IS_ERR(page))
 		goto out;
-	wait_on_page_locked(page);
-	if (!PageUptodate(page) || PageError(page)) {
+
+	oldfs = get_fs();
+	set_fs(KERNEL_DS);
+	ret = vfs_read(file, (char __user*) page_address(page), count, &pos);
+	set_fs(oldfs);
+
+	if (ret >= 0 && ret != count)
+		ret = -EIO;
+	if (ret < 0) {
+		put_page(page);
+		page = ERR_PTR(ret);
+		goto out;
+	}
+	bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
+	if (!bh) {
 		put_page(page);
-		page = ERR_PTR(-EIO);
+		page = ERR_PTR(-ENOMEM);
 		goto out;
 	}
+	attach_page_buffers(page, bh);
+	block = index << (PAGE_SHIFT - inode->i_blkbits);
+	while (bh) {
+		if (count == 0)
+			bh->b_blocknr = 0;
+		else {
+			bh->b_blocknr = bmap(inode, block);
+			if (bh->b_blocknr == 0) {
+				/* Cannot use this file! */
+				free_buffers(page);
+				page = ERR_PTR(-EINVAL);
+				goto out;
+			}
+			bh->b_bdev = inode->i_sb->s_bdev;
+			if (count < (1<<inode->i_blkbits))
+				count = 0;
+			else
+				count -= (1<<inode->i_blkbits);
+
+			bh->b_end_io = end_bitmap_write;
+			bh->b_private = bitmap;
+		}
+		block++;
+		bh = bh->b_this_page;
+	}
 
-	if (index > end_index) /* we have read beyond EOF */
-		*bytes_read = 0;
-	else if (index == end_index) /* possible short read */
-		*bytes_read = isize & ~PAGE_MASK;
-	else
-		*bytes_read = PAGE_SIZE; /* got a full page */
+	page->index = index;
 out:
 	if (IS_ERR(page))
 		printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
@@ -418,16 +479,14 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 	char *reason = NULL;
 	bitmap_super_t *sb;
 	unsigned long chunksize, daemon_sleep, write_behind;
-	unsigned long bytes_read;
 	unsigned long long events;
 	int err = -EINVAL;
 
 	/* page 0 is the superblock, read it... */
 	if (bitmap->file)
-		bitmap->sb_page = read_page(bitmap->file, 0, &bytes_read);
+		bitmap->sb_page = read_page(bitmap->file, 0, bitmap, PAGE_SIZE);
 	else {
 		bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
-		bytes_read = PAGE_SIZE;
 	}
 	if (IS_ERR(bitmap->sb_page)) {
 		err = PTR_ERR(bitmap->sb_page);
@@ -437,13 +496,6 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 
 	sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 
-	if (bytes_read < sizeof(*sb)) { /* short read */
-		printk(KERN_INFO "%s: bitmap file superblock truncated\n",
-			bmname(bitmap));
-		err = -ENOSPC;
-		goto out;
-	}
-
 	chunksize = le32_to_cpu(sb->chunksize);
 	daemon_sleep = le32_to_cpu(sb->daemon_sleep);
 	write_behind = le32_to_cpu(sb->write_behind);
@@ -589,37 +641,12 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
 
 	while (pages--)
 		if (map[pages]->index != 0) /* 0 is sb_page, release it below */
-			put_page(map[pages]);
+			free_buffers(map[pages]);
 	kfree(map);
 	kfree(attr);
 
-	safe_put_page(sb_page);
-}
-
-/* dequeue the next item in a page list -- don't call from irq context */
-static struct page_list *dequeue_page(struct bitmap *bitmap)
-{
-	struct page_list *item = NULL;
-	struct list_head *head = &bitmap->complete_pages;
-
-	spin_lock(&bitmap->write_lock);
-	if (list_empty(head))
-		goto out;
-	item = list_entry(head->prev, struct page_list, list);
-	list_del(head->prev);
-out:
-	spin_unlock(&bitmap->write_lock);
-	return item;
-}
-
-static void drain_write_queues(struct bitmap *bitmap)
-{
-	struct page_list *item;
-
-	while ((item = dequeue_page(bitmap))) {
-		/* don't bother to wait */
-		mempool_free(item, bitmap->write_pool);
-	}
+	if (sb_page)
+		free_buffers(sb_page);
 }
 
 static void bitmap_file_put(struct bitmap *bitmap)
@@ -632,12 +659,16 @@ static void bitmap_file_put(struct bitmap *bitmap)
 	bitmap->file = NULL;
 	spin_unlock_irqrestore(&bitmap->lock, flags);
 
-	drain_write_queues(bitmap);
-
+	if (file)
+		wait_event(bitmap->write_wait,
+			   atomic_read(&bitmap->pending_writes)==0);
 	bitmap_file_unmap(bitmap);
 
-	if (file)
+	if (file) {
+		struct inode *inode = file->f_dentry->d_inode;
+		invalidate_inode_pages(inode->i_mapping);
 		fput(file);
+	}
 }
 
 
@@ -728,8 +759,6 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 
 }
 
-static void bitmap_writeback(struct bitmap *bitmap);
-
 /* this gets called when the md device is ready to unplug its underlying
  * (slave) device queues -- before we let any writes go down, we need to
  * sync the dirty pages of the bitmap file to disk */
@@ -761,24 +790,18 @@ int bitmap_unplug(struct bitmap *bitmap)
 			wait = 1;
 		spin_unlock_irqrestore(&bitmap->lock, flags);
 
-		if (dirty | need_write) {
+		if (dirty | need_write)
 			err = write_page(bitmap, page, 0);
-			if (err == -EAGAIN) {
-				if (dirty)
-					err = write_page(bitmap, page, 1);
-				else
-					err = 0;
-			}
-			if (err)
-				return 1;
-		}
 	}
 	if (wait) { /* if any writes were performed, we need to wait on them */
 		if (bitmap->file)
-			bitmap_writeback(bitmap);
+			wait_event(bitmap->write_wait,
+				   atomic_read(&bitmap->pending_writes)==0);
 		else
 			md_super_wait(bitmap->mddev);
 	}
+	if (bitmap->flags & BITMAP_WRITE_ERROR)
+		bitmap_file_kick(bitmap);
 	return 0;
 }
 
@@ -800,7 +823,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 	struct page *page = NULL, *oldpage = NULL;
 	unsigned long num_pages, bit_cnt = 0;
 	struct file *file;
-	unsigned long bytes, offset, dummy;
+	unsigned long bytes, offset;
 	int outofdate;
 	int ret = -ENOSPC;
 	void *paddr;
@@ -853,7 +876,12 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 		index = file_page_index(i);
 		bit = file_page_offset(i);
 		if (index != oldindex) { /* this is a new page, read it in */
+			int count;
 			/* unmap the old page, we're done with it */
+			if (index == num_pages-1)
+				count = bytes - index * PAGE_SIZE;
+			else
+				count = PAGE_SIZE;
 			if (index == 0) {
 				/*
 				 * if we're here then the superblock page
@@ -863,7 +891,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 				page = bitmap->sb_page;
 				offset = sizeof(bitmap_super_t);
 			} else if (file) {
-				page = read_page(file, index, &dummy);
+				page = read_page(file, index, bitmap, count);
 				offset = 0;
 			} else {
 				page = read_sb_page(bitmap->mddev, bitmap->offset, index);
@@ -999,9 +1027,6 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 				spin_unlock_irqrestore(&bitmap->lock, flags);
 				if (need_write) {
 					switch (write_page(bitmap, page, 0)) {
-					case -EAGAIN:
-						set_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
-						break;
 					case 0:
 						break;
 					default:
@@ -1017,10 +1042,6 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 					clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 					spin_unlock_irqrestore(&bitmap->lock, flags);
 					err = write_page(bitmap, lastpage, 0);
-					if (err == -EAGAIN) {
-						err = 0;
-						set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
-					}
 				} else {
 					set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 					spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1070,10 +1091,6 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 			clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 			spin_unlock_irqrestore(&bitmap->lock, flags);
 			err = write_page(bitmap, lastpage, 0);
-			if (err == -EAGAIN) {
-				set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
-				err = 0;
-			}
 		} else {
 			set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
 			spin_unlock_irqrestore(&bitmap->lock, flags);
@@ -1083,32 +1100,6 @@ int bitmap_daemon_work(struct bitmap *bitmap)
 	return err;
 }
 
-static void bitmap_writeback(struct bitmap *bitmap)
-{
-	struct page *page;
-	struct page_list *item;
-	int err = 0;
-
-	PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
-	/* wait on bitmap page writebacks */
-	while ((item = dequeue_page(bitmap))) {
-		page = item->page;
-		mempool_free(item, bitmap->write_pool);
-		PRINTK("wait on page writeback: %p\n", page);
-		wait_on_page_writeback(page);
-		PRINTK("finished page writeback: %p\n", page);
-
-		err = PageError(page);
-		if (err) {
-			printk(KERN_WARNING "%s: bitmap file writeback "
-			       "failed (page %lu): %d\n",
-			       bmname(bitmap), page->index, err);
-			bitmap_file_kick(bitmap);
-			break;
-		}
-	}
-}
-
 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
 					    sector_t offset, int *blocks,
 					    int create)
@@ -1377,8 +1368,6 @@ static void bitmap_free(struct bitmap *bitmap)
 
 	/* free all allocated memory */
 
-	mempool_destroy(bitmap->write_pool);
-
 	if (bp) /* deallocate the page memory */
 		for (k = 0; k < pages; k++)
 			if (bp[k].map && !bp[k].hijacked)
@@ -1428,17 +1417,13 @@ int bitmap_create(mddev_t *mddev)
 	spin_lock_init(&bitmap->lock);
 	bitmap->mddev = mddev;
 
-	spin_lock_init(&bitmap->write_lock);
-	INIT_LIST_HEAD(&bitmap->complete_pages);
-	bitmap->write_pool = mempool_create_kmalloc_pool(WRITE_POOL_SIZE,
-						sizeof(struct page_list));
-	err = -ENOMEM;
-	if (!bitmap->write_pool)
-		goto error;
-
 	bitmap->file = file;
 	bitmap->offset = mddev->bitmap_offset;
 	if (file) get_file(file);
+
+	/* Ensure we read fresh data */
+	invalidate_inode_pages(file->f_dentry->d_inode->i_mapping);
+
 	/* read superblock from bitmap file (this sets bitmap->chunksize) */
 	err = bitmap_read_sb(bitmap);
 	if (err)
@@ -1461,6 +1446,9 @@ int bitmap_create(mddev_t *mddev)
 
 	bitmap->syncchunk = ~0UL;
 
+	atomic_set(&bitmap->pending_writes, 0);
+	init_waitqueue_head(&bitmap->write_wait);
+
 #ifdef INJECT_FATAL_FAULT_1
 	bitmap->bp = NULL;
 #else
@@ -1503,4 +1491,3 @@ EXPORT_SYMBOL(bitmap_start_sync);
 EXPORT_SYMBOL(bitmap_end_sync);
 EXPORT_SYMBOL(bitmap_unplug);
 EXPORT_SYMBOL(bitmap_close_sync);
-EXPORT_SYMBOL(bitmap_daemon_work);
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 9c8907c..63df898 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -140,6 +140,7 @@ typedef __u16 bitmap_counter_t;
 enum bitmap_state {
 	BITMAP_ACTIVE = 0x001, /* the bitmap is in use */
 	BITMAP_STALE  = 0x002,  /* the bitmap file is out of date or had -EIO */
+	BITMAP_WRITE_ERROR = 0x004, /* A write error has occurred */
 	BITMAP_HOSTENDIAN = 0x8000,
 };
 
@@ -244,9 +245,9 @@ struct bitmap {
 	unsigned long daemon_lastrun; /* jiffies of last run */
 	unsigned long daemon_sleep; /* how many seconds between updates? */
 
-	spinlock_t write_lock;
-	struct list_head complete_pages;
-	mempool_t *write_pool;
+	atomic_t pending_writes; /* pending writes to the bitmap file */
+	wait_queue_head_t write_wait;
+
 };
 
 /* the bitmap API */