[PATCH] Trivial optimization of ll_rw_block()
[safe/jmp/linux-2.6] / fs / buffer.c
index f961605..62cfd17 100644 (file)
@@ -26,6 +26,7 @@
 #include <linux/percpu.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
+#include <linux/capability.h>
 #include <linux/blkdev.h>
 #include <linux/file.h>
 #include <linux/quotaops.h>
@@ -40,6 +41,7 @@
 #include <linux/cpu.h>
 #include <linux/bitops.h>
 #include <linux/mpage.h>
+#include <linux/bit_spinlock.h>
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
 static void invalidate_bh_lrus(void);
@@ -95,7 +97,7 @@ static void
 __clear_page_buffers(struct page *page)
 {
        ClearPagePrivate(page);
-       page->private = 0;
+       set_page_private(page, 0);
        page_cache_release(page);
 }
 
@@ -152,14 +154,8 @@ int sync_blockdev(struct block_device *bdev)
 {
        int ret = 0;
 
-       if (bdev) {
-               int err;
-
-               ret = filemap_fdatawrite(bdev->bd_inode->i_mapping);
-               err = filemap_fdatawait(bdev->bd_inode->i_mapping);
-               if (!ret)
-                       ret = err;
-       }
+       if (bdev)
+               ret = filemap_write_and_wait(bdev->bd_inode->i_mapping);
        return ret;
 }
 EXPORT_SYMBOL(sync_blockdev);
@@ -218,7 +214,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
        sb = get_super(bdev);
        if (sb && !(sb->s_flags & MS_RDONLY)) {
                sb->s_frozen = SB_FREEZE_WRITE;
-               wmb();
+               smp_wmb();
 
                sync_inodes_sb(sb, 0);
                DQUOT_SYNC(sb);
@@ -235,7 +231,7 @@ struct super_block *freeze_bdev(struct block_device *bdev)
                sync_inodes_sb(sb, 1);
 
                sb->s_frozen = SB_FREEZE_TRANS;
-               wmb();
+               smp_wmb();
 
                sync_blockdev(sb->s_bdev);
 
@@ -263,7 +259,7 @@ void thaw_bdev(struct block_device *bdev, struct super_block *sb)
                if (sb->s_op->unlockfs)
                        sb->s_op->unlockfs(sb);
                sb->s_frozen = SB_UNFROZEN;
-               wmb();
+               smp_wmb();
                wake_up(&sb->s_wait_unfrozen);
                drop_super(sb);
        }
@@ -278,7 +274,7 @@ EXPORT_SYMBOL(thaw_bdev);
  */
 static void do_sync(unsigned long wait)
 {
-       wakeup_bdflush(0);
+       wakeup_pdflush(0);
        sync_inodes(0);         /* All mappings, inodes and their blockdevs */
        DQUOT_SYNC(NULL);
        sync_supers();          /* Write the superblocks */
@@ -331,7 +327,7 @@ int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
        return ret;
 }
 
-asmlinkage long sys_fsync(unsigned int fd)
+static long do_fsync(unsigned int fd, int datasync)
 {
        struct file * file;
        struct address_space *mapping;
@@ -342,14 +338,14 @@ asmlinkage long sys_fsync(unsigned int fd)
        if (!file)
                goto out;
 
-       mapping = file->f_mapping;
-
        ret = -EINVAL;
        if (!file->f_op || !file->f_op->fsync) {
                /* Why?  We can still call filemap_fdatawrite */
                goto out_putf;
        }
 
+       mapping = file->f_mapping;
+
        current->flags |= PF_SYNCWRITE;
        ret = filemap_fdatawrite(mapping);
 
@@ -357,11 +353,11 @@ asmlinkage long sys_fsync(unsigned int fd)
         * We need to protect against concurrent writers,
         * which could cause livelocks in fsync_buffers_list
         */
-       down(&mapping->host->i_sem);
-       err = file->f_op->fsync(file, file->f_dentry, 0);
+       mutex_lock(&mapping->host->i_mutex);
+       err = file->f_op->fsync(file, file->f_dentry, datasync);
        if (!ret)
                ret = err;
-       up(&mapping->host->i_sem);
+       mutex_unlock(&mapping->host->i_mutex);
        err = filemap_fdatawait(mapping);
        if (!ret)
                ret = err;
@@ -373,39 +369,14 @@ out:
        return ret;
 }
 
-asmlinkage long sys_fdatasync(unsigned int fd)
+asmlinkage long sys_fsync(unsigned int fd)
 {
-       struct file * file;
-       struct address_space *mapping;
-       int ret, err;
-
-       ret = -EBADF;
-       file = fget(fd);
-       if (!file)
-               goto out;
-
-       ret = -EINVAL;
-       if (!file->f_op || !file->f_op->fsync)
-               goto out_putf;
-
-       mapping = file->f_mapping;
-
-       current->flags |= PF_SYNCWRITE;
-       ret = filemap_fdatawrite(mapping);
-       down(&mapping->host->i_sem);
-       err = file->f_op->fsync(file, file->f_dentry, 1);
-       if (!ret)
-               ret = err;
-       up(&mapping->host->i_sem);
-       err = filemap_fdatawait(mapping);
-       if (!ret)
-               ret = err;
-       current->flags &= ~PF_SYNCWRITE;
+       return do_fsync(fd, 0);
+}
 
-out_putf:
-       fput(file);
-out:
-       return ret;
+asmlinkage long sys_fdatasync(unsigned int fd)
+{
+       return do_fsync(fd, 1);
 }
 
 /*
@@ -420,7 +391,7 @@ out:
  * private_lock is contended then so is mapping->tree_lock).
  */
 static struct buffer_head *
-__find_get_block_slow(struct block_device *bdev, sector_t block, int unused)
+__find_get_block_slow(struct block_device *bdev, sector_t block)
 {
        struct inode *bd_inode = bdev->bd_inode;
        struct address_space *bd_mapping = bd_inode->i_mapping;
@@ -522,13 +493,13 @@ static void free_more_memory(void)
        struct zone **zones;
        pg_data_t *pgdat;
 
-       wakeup_bdflush(1024);
+       wakeup_pdflush(1024);
        yield();
 
        for_each_pgdat(pgdat) {
-               zones = pgdat->node_zonelists[GFP_NOFS&GFP_ZONEMASK].zones;
+               zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones;
                if (*zones)
-                       try_to_free_pages(zones, GFP_NOFS, 0);
+                       try_to_free_pages(zones, GFP_NOFS);
        }
 }
 
@@ -538,8 +509,8 @@ static void free_more_memory(void)
  */
 static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 {
-       static DEFINE_SPINLOCK(page_uptodate_lock);
        unsigned long flags;
+       struct buffer_head *first;
        struct buffer_head *tmp;
        struct page *page;
        int page_uptodate = 1;
@@ -561,7 +532,9 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
         * two buffer heads end IO at almost the same time and both
         * decide that the page is now completely done.
         */
-       spin_lock_irqsave(&page_uptodate_lock, flags);
+       first = page_buffers(page);
+       local_irq_save(flags);
+       bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
        clear_buffer_async_read(bh);
        unlock_buffer(bh);
        tmp = bh;
@@ -574,7 +547,8 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
                }
                tmp = tmp->b_this_page;
        } while (tmp != bh);
-       spin_unlock_irqrestore(&page_uptodate_lock, flags);
+       bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+       local_irq_restore(flags);
 
        /*
         * If none of the buffers had errors and they are all
@@ -586,7 +560,8 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
        return;
 
 still_busy:
-       spin_unlock_irqrestore(&page_uptodate_lock, flags);
+       bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+       local_irq_restore(flags);
        return;
 }
 
@@ -597,8 +572,8 @@ still_busy:
 void end_buffer_async_write(struct buffer_head *bh, int uptodate)
 {
        char b[BDEVNAME_SIZE];
-       static DEFINE_SPINLOCK(page_uptodate_lock);
        unsigned long flags;
+       struct buffer_head *first;
        struct buffer_head *tmp;
        struct page *page;
 
@@ -619,7 +594,10 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate)
                SetPageError(page);
        }
 
-       spin_lock_irqsave(&page_uptodate_lock, flags);
+       first = page_buffers(page);
+       local_irq_save(flags);
+       bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+
        clear_buffer_async_write(bh);
        unlock_buffer(bh);
        tmp = bh->b_this_page;
@@ -630,12 +608,14 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate)
                }
                tmp = tmp->b_this_page;
        }
-       spin_unlock_irqrestore(&page_uptodate_lock, flags);
+       bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+       local_irq_restore(flags);
        end_page_writeback(page);
        return;
 
 still_busy:
-       spin_unlock_irqrestore(&page_uptodate_lock, flags);
+       bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+       local_irq_restore(flags);
        return;
 }
 
@@ -774,15 +754,14 @@ repeat:
 /**
  * sync_mapping_buffers - write out and wait upon a mapping's "associated"
  *                        buffers
- * @buffer_mapping - the mapping which backs the buffers' data
- * @mapping - the mapping which wants those buffers written
+ * @mapping: the mapping which wants those buffers written
  *
  * Starts I/O against the buffers at mapping->private_list, and waits upon
  * that I/O.
  *
- * Basically, this is a convenience function for fsync().  @buffer_mapping is
- * the blockdev which "owns" the buffers and @mapping is a file or directory
- * which needs those buffers to be written for a successful fsync().
+ * Basically, this is a convenience function for fsync().
+ * @mapping is a file or directory which needs those buffers to be written for
+ * a successful fsync().
  */
 int sync_mapping_buffers(struct address_space *mapping)
 {
@@ -934,8 +913,7 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
                                 * contents - it is a noop if I/O is still in
                                 * flight on potentially older contents.
                                 */
-                               wait_on_buffer(bh);
-                               ll_rw_block(WRITE, 1, &bh);
+                               ll_rw_block(SWRITE, 1, &bh);
                                brelse(bh);
                                spin_lock(lock);
                        }
@@ -1044,12 +1022,13 @@ try_again:
 
                bh->b_state = 0;
                atomic_set(&bh->b_count, 0);
+               bh->b_private = NULL;
                bh->b_size = size;
 
                /* Link the buffer to its page */
                set_bh_page(bh, page, offset);
 
-               bh->b_end_io = NULL;
+               init_buffer(bh, NULL, NULL);
        }
        return head;
 /*
@@ -1187,7 +1166,7 @@ failed:
  * some of those buffers may be aliases of filesystem data.
  * grow_dev_page() will go BUG() if this happens.
  */
-static inline int
+static int
 grow_buffers(struct block_device *bdev, sector_t block, int size)
 {
        struct page *page;
@@ -1211,7 +1190,7 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
        return 1;
 }
 
-struct buffer_head *
+static struct buffer_head *
 __getblk_slow(struct block_device *bdev, sector_t block, int size)
 {
        /* Size must be multiple of hard sectorsize */
@@ -1263,6 +1242,7 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
 
 /**
  * mark_buffer_dirty - mark a buffer_head as needing writeout
+ * @bh: the buffer_head to mark dirty
  *
  * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
  * backing page dirty, then tag the page as dirty in its address_space's radix
@@ -1412,7 +1392,7 @@ static void bh_lru_install(struct buffer_head *bh)
 /*
  * Look up the bh in this cpu's LRU.  If it's there, move it to the head.
  */
-static inline struct buffer_head *
+static struct buffer_head *
 lookup_bh_lru(struct block_device *bdev, sector_t block, int size)
 {
        struct buffer_head *ret = NULL;
@@ -1454,7 +1434,7 @@ __find_get_block(struct block_device *bdev, sector_t block, int size)
        struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
 
        if (bh == NULL) {
-               bh = __find_get_block_slow(bdev, block, size);
+               bh = __find_get_block_slow(bdev, block);
                if (bh)
                        bh_lru_install(bh);
        }
@@ -1494,13 +1474,16 @@ EXPORT_SYMBOL(__getblk);
 void __breadahead(struct block_device *bdev, sector_t block, int size)
 {
        struct buffer_head *bh = __getblk(bdev, block, size);
-       ll_rw_block(READA, 1, &bh);
-       brelse(bh);
+       if (likely(bh)) {
+               ll_rw_block(READA, 1, &bh);
+               brelse(bh);
+       }
 }
 EXPORT_SYMBOL(__breadahead);
 
 /**
  *  __bread() - reads a specified block and returns the bh
+ *  @bdev: the block_device to read from
  *  @block: number of block
  *  @size: size (in bytes) to read
  * 
@@ -1512,7 +1495,7 @@ __bread(struct block_device *bdev, sector_t block, int size)
 {
        struct buffer_head *bh = __getblk(bdev, block, size);
 
-       if (!buffer_uptodate(bh))
+       if (likely(bh) && !buffer_uptodate(bh))
                bh = __bread_slow(bh);
        return bh;
 }
@@ -1559,7 +1542,7 @@ EXPORT_SYMBOL(set_bh_page);
 /*
  * Called when truncating a buffer on a page completely.
  */
-static inline void discard_buffer(struct buffer_head * bh)
+static void discard_buffer(struct buffer_head * bh)
 {
        lock_buffer(bh);
        clear_buffer_dirty(bh);
@@ -1586,7 +1569,7 @@ static inline void discard_buffer(struct buffer_head * bh)
  *
  * NOTE: @gfp_mask may go away, and this function may become non-blocking.
  */
-int try_to_release_page(struct page *page, int gfp_mask)
+int try_to_release_page(struct page *page, gfp_t gfp_mask)
 {
        struct address_space * const mapping = page->mapping;
 
@@ -1652,6 +1635,15 @@ out:
 }
 EXPORT_SYMBOL(block_invalidatepage);
 
+int do_invalidatepage(struct page *page, unsigned long offset)
+{
+       int (*invalidatepage)(struct page *, unsigned long);
+       invalidatepage = page->mapping->a_ops->invalidatepage;
+       if (invalidatepage == NULL)
+               invalidatepage = block_invalidatepage;
+       return (*invalidatepage)(page, offset);
+}
+
 /*
  * We attach and possibly dirty the buffers atomically wrt
  * __set_page_dirty_buffers() via private_lock.  try_to_free_buffers
@@ -1709,7 +1701,7 @@ void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
 
        might_sleep();
 
-       old_bh = __find_get_block_slow(bdev, block, 0);
+       old_bh = __find_get_block_slow(bdev, block);
        if (old_bh) {
                clear_buffer_dirty(old_bh);
                wait_on_buffer(old_bh);
@@ -1772,7 +1764,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
         * handle that here by just cleaning them.
         */
 
-       block = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+       block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
        head = page_buffers(page);
        bh = head;
 
@@ -1808,7 +1800,6 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
        } while (bh != head);
 
        do {
-               get_bh(bh);
                if (!buffer_mapped(bh))
                        continue;
                /*
@@ -1837,7 +1828,6 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
         */
        BUG_ON(PageWriteback(page));
        set_page_writeback(page);
-       unlock_page(page);
 
        do {
                struct buffer_head *next = bh->b_this_page;
@@ -1845,9 +1835,9 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
                        submit_bh(WRITE, bh);
                        nr_underway++;
                }
-               put_bh(bh);
                bh = next;
        } while (bh != head);
+       unlock_page(page);
 
        err = 0;
 done:
@@ -1886,7 +1876,6 @@ recover:
        bh = head;
        /* Recovery: lock and submit the mapped buffers */
        do {
-               get_bh(bh);
                if (buffer_mapped(bh) && buffer_dirty(bh)) {
                        lock_buffer(bh);
                        mark_buffer_async_write(bh);
@@ -1909,7 +1898,6 @@ recover:
                        submit_bh(WRITE, bh);
                        nr_underway++;
                }
-               put_bh(bh);
                bh = next;
        } while (bh != head);
        goto done;
@@ -1952,9 +1940,8 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
                if (!buffer_mapped(bh)) {
                        err = get_block(inode, block, bh, 1);
                        if (err)
-                               goto out;
+                               break;
                        if (buffer_new(bh)) {
-                               clear_buffer_new(bh);
                                unmap_underlying_metadata(bh->b_bdev,
                                                        bh->b_blocknr);
                                if (PageUptodate(page)) {
@@ -1994,10 +1981,17 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
        while(wait_bh > wait) {
                wait_on_buffer(*--wait_bh);
                if (!buffer_uptodate(*wait_bh))
-                       return -EIO;
+                       err = -EIO;
        }
-       return 0;
-out:
+       if (!err) {
+               bh = head;
+               do {
+                       if (buffer_new(bh))
+                               clear_buffer_new(bh);
+               } while ((bh = bh->b_this_page) != head);
+               return 0;
+       }
+       /* Error case: */
        /*
         * Zero out any newly allocated blocks to avoid exposing stale
         * data.  If BH_New is set, we know that the block was newly
@@ -2078,8 +2072,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
        int nr, i;
        int fully_mapped = 1;
 
-       if (!PageLocked(page))
-               PAGE_BUG(page);
+       BUG_ON(!PageLocked(page));
        blocksize = 1 << inode->i_blkbits;
        if (!page_has_buffers(page))
                create_empty_buffers(page, blocksize, 0);
@@ -2096,9 +2089,12 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
                        continue;
 
                if (!buffer_mapped(bh)) {
+                       int err = 0;
+
                        fully_mapped = 0;
                        if (iblock < lblock) {
-                               if (get_block(inode, iblock, bh, 0))
+                               err = get_block(inode, iblock, bh, 0);
+                               if (err)
                                        SetPageError(page);
                        }
                        if (!buffer_mapped(bh)) {
@@ -2106,7 +2102,8 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
                                memset(kaddr + i * blocksize, 0, blocksize);
                                flush_dcache_page(page);
                                kunmap_atomic(kaddr, KM_USER0);
-                               set_buffer_uptodate(bh);
+                               if (!err)
+                                       set_buffer_uptodate(bh);
                                continue;
                        }
                        /*
@@ -2159,11 +2156,12 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
  * truncates.  Uses prepare/commit_write to allow the filesystem to
  * deal with the hole.  
  */
-int generic_cont_expand(struct inode *inode, loff_t size)
+static int __generic_cont_expand(struct inode *inode, loff_t size,
+                                pgoff_t index, unsigned int offset)
 {
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
-       unsigned long index, offset, limit;
+       unsigned long limit;
        int err;
 
        err = -EFBIG;
@@ -2175,24 +2173,24 @@ int generic_cont_expand(struct inode *inode, loff_t size)
        if (size > inode->i_sb->s_maxbytes)
                goto out;
 
-       offset = (size & (PAGE_CACHE_SIZE-1)); /* Within page */
-
-       /* ugh.  in prepare/commit_write, if from==to==start of block, we 
-       ** skip the prepare.  make sure we never send an offset for the start
-       ** of a block
-       */
-       if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
-               offset++;
-       }
-       index = size >> PAGE_CACHE_SHIFT;
        err = -ENOMEM;
        page = grab_cache_page(mapping, index);
        if (!page)
                goto out;
        err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
-       if (!err) {
-               err = mapping->a_ops->commit_write(NULL, page, offset, offset);
+       if (err) {
+               /*
+                * ->prepare_write() may have instantiated a few blocks
+                * outside i_size.  Trim these off again.
+                */
+               unlock_page(page);
+               page_cache_release(page);
+               vmtruncate(inode, inode->i_size);
+               goto out;
        }
+
+       err = mapping->a_ops->commit_write(NULL, page, offset, offset);
+
        unlock_page(page);
        page_cache_release(page);
        if (err > 0)
@@ -2201,6 +2199,36 @@ out:
        return err;
 }
 
+int generic_cont_expand(struct inode *inode, loff_t size)
+{
+       pgoff_t index;
+       unsigned int offset;
+
+       offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
+
+       /* ugh.  in prepare/commit_write, if from==to==start of block, we
+       ** skip the prepare.  make sure we never send an offset for the start
+       ** of a block
+       */
+       if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
+               /* caller must handle this extra byte. */
+               offset++;
+       }
+       index = size >> PAGE_CACHE_SHIFT;
+
+       return __generic_cont_expand(inode, size, index, offset);
+}
+
+int generic_cont_expand_simple(struct inode *inode, loff_t size)
+{
+       loff_t pos = size - 1;
+       pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+       unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
+
+       /* prepare/commit_write can handle even if from==to==start of block. */
+       return __generic_cont_expand(inode, size, index, offset);
+}
+
 /*
  * For moronic filesystems that do not allow holes in file.
  * We may have to extend the file.
@@ -2312,7 +2340,7 @@ int generic_commit_write(struct file *file, struct page *page,
        __block_commit_write(inode,page,from,to);
        /*
         * No need to use i_size_read() here, the i_size
-        * cannot change under us because we hold i_sem.
+        * cannot change under us because we hold i_mutex.
         */
        if (pos > inode->i_size) {
                i_size_write(inode, pos);
@@ -2609,7 +2637,7 @@ int block_truncate_page(struct address_space *mapping,
        pgoff_t index = from >> PAGE_CACHE_SHIFT;
        unsigned offset = from & (PAGE_CACHE_SIZE-1);
        unsigned blocksize;
-       pgoff_t iblock;
+       sector_t iblock;
        unsigned length, pos;
        struct inode *inode = mapping->host;
        struct page *page;
@@ -2625,7 +2653,7 @@ int block_truncate_page(struct address_space *mapping,
                return 0;
 
        length = blocksize - length;
-       iblock = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+       iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
        
        page = grab_cache_page(mapping, index);
        err = -ENOMEM;
@@ -2706,7 +2734,7 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
                 * they may have been added in ext3_writepage().  Make them
                 * freeable here, so the page does not leak.
                 */
-               block_invalidatepage(page, 0);
+               do_invalidatepage(page, 0);
                unlock_page(page);
                return 0; /* don't care */
        }
@@ -2803,21 +2831,22 @@ int submit_bh(int rw, struct buffer_head * bh)
 
 /**
  * ll_rw_block: low-level access to block devices (DEPRECATED)
- * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
+ * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
  * @nr: number of &struct buffer_heads in the array
  * @bhs: array of pointers to &struct buffer_head
  *
- * ll_rw_block() takes an array of pointers to &struct buffer_heads,
- * and requests an I/O operation on them, either a %READ or a %WRITE.
- * The third %READA option is described in the documentation for
- * generic_make_request() which ll_rw_block() calls.
+ * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
+ * requests an I/O operation on them, either a %READ or a %WRITE.  The third
+ * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
+ * are sent to disk. The fourth %READA option is described in the documentation
+ * for generic_make_request() which ll_rw_block() calls.
  *
  * This function drops any buffer that it cannot get a lock on (with the
- * BH_Lock state bit), any buffer that appears to be clean when doing a
- * write request, and any buffer that appears to be up-to-date when doing
- * read request.  Further it marks as clean buffers that are processed for
- * writing (the buffer cache won't assume that they are actually clean until
- * the buffer gets unlocked).
+ * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
+ * clean when doing a write request, and any buffer that appears to be
+ * up-to-date when doing read request.  Further it marks as clean buffers that
+ * are processed for writing (the buffer cache won't assume that they are
+ * actually clean until the buffer gets unlocked).
  *
  * ll_rw_block sets b_end_io to simple completion handler that marks
  * the buffer up-to-date (if approriate), unlocks the buffer and wakes
@@ -2833,25 +2862,27 @@ void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
        for (i = 0; i < nr; i++) {
                struct buffer_head *bh = bhs[i];
 
-               if (test_set_buffer_locked(bh))
+               if (rw == SWRITE)
+                       lock_buffer(bh);
+               else if (test_set_buffer_locked(bh))
                        continue;
 
-               get_bh(bh);
-               if (rw == WRITE) {
-                       bh->b_end_io = end_buffer_write_sync;
+               if (rw == WRITE || rw == SWRITE) {
                        if (test_clear_buffer_dirty(bh)) {
+                               bh->b_end_io = end_buffer_write_sync;
+                               get_bh(bh);
                                submit_bh(WRITE, bh);
                                continue;
                        }
                } else {
-                       bh->b_end_io = end_buffer_read_sync;
                        if (!buffer_uptodate(bh)) {
+                               bh->b_end_io = end_buffer_read_sync;
+                               get_bh(bh);
                                submit_bh(rw, bh);
                                continue;
                        }
                }
                unlock_buffer(bh);
-               put_bh(bh);
        }
 }
 
@@ -2917,7 +2948,7 @@ drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
 
        bh = head;
        do {
-               if (buffer_write_io_error(bh))
+               if (buffer_write_io_error(bh) && page->mapping)
                        set_bit(AS_EIO, &page->mapping->flags);
                if (buffer_busy(bh))
                        goto failed;
@@ -3020,6 +3051,66 @@ asmlinkage long sys_bdflush(int func, long data)
 }
 
 /*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+#ifdef CONFIG_MIGRATION
+int buffer_migrate_page(struct page *newpage, struct page *page)
+{
+       struct address_space *mapping = page->mapping;
+       struct buffer_head *bh, *head;
+
+       if (!mapping)
+               return -EAGAIN;
+
+       if (!page_has_buffers(page))
+               return migrate_page(newpage, page);
+
+       head = page_buffers(page);
+
+       if (migrate_page_remove_references(newpage, page, 3))
+               return -EAGAIN;
+
+       bh = head;
+       do {
+               get_bh(bh);
+               lock_buffer(bh);
+               bh = bh->b_this_page;
+
+       } while (bh != head);
+
+       ClearPagePrivate(page);
+       set_page_private(newpage, page_private(page));
+       set_page_private(page, 0);
+       put_page(page);
+       get_page(newpage);
+
+       bh = head;
+       do {
+               set_bh_page(bh, newpage, bh_offset(bh));
+               bh = bh->b_this_page;
+
+       } while (bh != head);
+
+       SetPagePrivate(newpage);
+
+       migrate_page_copy(newpage, page);
+
+       bh = head;
+       do {
+               unlock_buffer(bh);
+               put_bh(bh);
+               bh = bh->b_this_page;
+
+       } while (bh != head);
+
+       return 0;
+}
+EXPORT_SYMBOL(buffer_migrate_page);
+#endif
+
+/*
  * Buffer-head allocation
  */
 static kmem_cache_t *bh_cachep;
@@ -3052,14 +3143,13 @@ static void recalc_bh_state(void)
        buffer_heads_over_limit = (tot > max_buffer_heads);
 }
        
-struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags)
+struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
 {
        struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags);
        if (ret) {
-               preempt_disable();
-               __get_cpu_var(bh_accounting).nr++;
+               get_cpu_var(bh_accounting).nr++;
                recalc_bh_state();
-               preempt_enable();
+               put_cpu_var(bh_accounting);
        }
        return ret;
 }
@@ -3069,10 +3159,9 @@ void free_buffer_head(struct buffer_head *bh)
 {
        BUG_ON(!list_empty(&bh->b_assoc_buffers));
        kmem_cache_free(bh_cachep, bh);
-       preempt_disable();
-       __get_cpu_var(bh_accounting).nr--;
+       get_cpu_var(bh_accounting).nr--;
        recalc_bh_state();
-       preempt_enable();
+       put_cpu_var(bh_accounting);
 }
 EXPORT_SYMBOL(free_buffer_head);
 
@@ -3115,7 +3204,7 @@ void __init buffer_init(void)
 
        bh_cachep = kmem_cache_create("buffer_head",
                        sizeof(struct buffer_head), 0,
-                       SLAB_PANIC, init_buffer_head, NULL);
+                       SLAB_RECLAIM_ACCOUNT|SLAB_PANIC, init_buffer_head, NULL);
 
        /*
         * Limit the bh occupancy to 10% of ZONE_NORMAL
@@ -3143,6 +3232,7 @@ EXPORT_SYMBOL(fsync_bdev);
 EXPORT_SYMBOL(generic_block_bmap);
 EXPORT_SYMBOL(generic_commit_write);
 EXPORT_SYMBOL(generic_cont_expand);
+EXPORT_SYMBOL(generic_cont_expand_simple);
 EXPORT_SYMBOL(init_buffer);
 EXPORT_SYMBOL(invalidate_bdev);
 EXPORT_SYMBOL(ll_rw_block);