2 files changed, 139 insertions, 151 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index e40d3e4b8d27..bedd66e9e8ac 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 9c8907ca60a7..63df898fe2e9 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 */