Use an atomic kmap for generic_file_write()

@@ -1065,6 +1065,22 @@ static inline int fault_in_pages_writeab
 	return ret;
 }
 
+static inline int fault_in_pages_readable(const char *uaddr, int size)
+{
+	volatile char c;
+	int ret;
+
+	ret = __get_user(c, (char *)uaddr);
+	if (ret == 0) {
+		const char *end = uaddr + size - 1;
+
+		if (((unsigned long)uaddr & PAGE_MASK) !=
+				((unsigned long)end & PAGE_MASK))
+		 	ret = __get_user(c, (char *)end);
+	}
+	return ret;
+}
+
 int file_read_actor(read_descriptor_t *desc, struct page *page,
 			unsigned long offset, unsigned long size)
 {

@@ -1883,6 +1899,29 @@ inline void remove_suid(struct dentry *d
 	}
 }
 
+static inline int
+filemap_copy_from_user(struct page *page, unsigned long offset,
+			const char *buf, unsigned bytes, int fault_expected)
+{
+	char *kaddr;
+	int left;
+
+	kaddr = kmap_atomic(page, KM_USER0);
+	left = __copy_from_user(kaddr + offset, buf, bytes);
+	kunmap_atomic(kaddr, KM_USER0);
+
+	if (left != 0) {
+		if (!fault_expected)
+			printk("%s: Unexpected page fault\n", __FUNCTION__);
+
+		/* Do it the slow way */
+		kaddr = kmap(page);
+		left = __copy_from_user(kaddr + offset, buf, bytes);
+		kunmap(page);
+	}
+	return left;
+}
+
 /*
  * Write to a file through the page cache. 
  *

@@ -2035,7 +2074,7 @@ ssize_t generic_file_write_nolock(struct
 		unsigned long index;
 		unsigned long offset;
 		long page_fault;
-		char *kaddr;
+		int fault_expected;	/* This is just debug */
 
 		offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
 		index = pos >> PAGE_CACHE_SHIFT;

@@ -2049,10 +2088,7 @@ ssize_t generic_file_write_nolock(struct
 		 * same page as we're writing to, without it being marked
 		 * up-to-date.
 		 */
-		{ volatile unsigned char dummy;
-			__get_user(dummy, buf);
-			__get_user(dummy, buf+bytes-1);
-		}
+		fault_expected = fault_in_pages_readable(buf, bytes);
 
 		page = __grab_cache_page(mapping, index, &cached_page, &lru_pvec);
 		if (!page) {

@@ -2060,22 +2096,20 @@ ssize_t generic_file_write_nolock(struct
 			break;
 		}
 
-		kaddr = kmap(page);
 		status = a_ops->prepare_write(file, page, offset, offset+bytes);
 		if (unlikely(status)) {
 			/*
 			 * prepare_write() may have instantiated a few blocks
 			 * outside i_size.  Trim these off again.
 			 */
-			kunmap(page);
 			unlock_page(page);
 			page_cache_release(page);
 			if (pos + bytes > inode->i_size)
 				vmtruncate(inode, inode->i_size);
 			break;
 		}
-		page_fault = __copy_from_user(kaddr + offset, buf, bytes);
-		flush_dcache_page(page);
+		page_fault = filemap_copy_from_user(page, offset,
+						buf, bytes, fault_expected);
 		status = a_ops->commit_write(file, page, offset, offset+bytes);
 		if (unlikely(page_fault)) {
 			status = -EFAULT;

@@ -2090,7 +2124,6 @@ ssize_t generic_file_write_nolock(struct
 				buf += status;
 			}
 		}
-		kunmap(page);
 		if (!PageReferenced(page))
 			SetPageReferenced(page);
 		unlock_page(page);

167 lines not on this page · raw message

@@ -1082,16 +1082,6 @@ static int ext3_prepare_write(struct fil
 	if (ext3_should_journal_data(inode)) {
 		ret = walk_page_buffers(handle, page_buffers(page),
 				from, to, NULL, do_journal_get_write_access);
-		if (ret) {
-			/*
-			 * We're going to fail this prepare_write(),
-			 * so commit_write() will not be called.
-			 * We need to undo block_prepare_write()'s kmap().
-			 * AKPM: Do we need to clear PageUptodate?  I don't
-			 * think so.
-			 */
-			kunmap(page);
-		}
 	}
 prepare_write_failed:
 	if (ret)

@@ -1151,7 +1141,6 @@ static int ext3_commit_write(struct file
 			from, to, &partial, commit_write_fn);
 		if (!partial)
 			SetPageUptodate(page);
-		kunmap(page);
 		if (pos > inode->i_size)
 			inode->i_size = pos;
 		EXT3_I(inode)->i_state |= EXT3_STATE_JDATA;

@@ -1162,17 +1151,8 @@ static int ext3_commit_write(struct file
 		}
 		/* Be careful here if generic_commit_write becomes a
 		 * required invocation after block_prepare_write. */
-		if (ret == 0) {
+		if (ret == 0)
 			ret = generic_commit_write(file, page, from, to);
-		} else {
-			/*
-			 * block_prepare_write() was called, but we're not
-			 * going to call generic_commit_write().  So we
-			 * need to perform generic_commit_write()'s kunmap
-			 * by hand.
-			 */
-			kunmap(page);
-		}
 	}
 	if (inode->i_size > EXT3_I(inode)->i_disksize) {
 		EXT3_I(inode)->i_disksize = inode->i_size;

@@ -1535,6 +1515,7 @@ static int ext3_block_truncate_page(hand
 	struct page *page;
 	struct buffer_head *bh;
 	int err;
+	void *kaddr;
 
 	blocksize = inode->i_sb->s_blocksize;
 	length = offset & (blocksize - 1);

@@ -1590,10 +1571,11 @@ static int ext3_block_truncate_page(hand
 		if (err)
 			goto unlock;
 	}
-	
-	memset(kmap(page) + offset, 0, length);
+
+	kaddr = kmap_atomic(page, KM_USER0);
+	memset(kaddr + offset, 0, length);
 	flush_dcache_page(page);
-	kunmap(page);
+	kunmap_atomic(kaddr, KM_USER0);
 
 	BUFFER_TRACE(bh, "zeroed end of block");
 

@@ -571,8 +571,8 @@ int ext2_make_empty(struct inode *inode,
 	struct page *page = grab_cache_page(mapping, 0);
 	unsigned chunk_size = ext2_chunk_size(inode);
 	struct ext2_dir_entry_2 * de;
-	char *base;
 	int err;
+	void *kaddr;
 
 	if (!page)
 		return -ENOMEM;

@@ -581,22 +581,21 @@ int ext2_make_empty(struct inode *inode,
 		unlock_page(page);
 		goto fail;
 	}
-	base = page_address(page);
-
-	de = (struct ext2_dir_entry_2 *) base;
+	kaddr = kmap_atomic(page, KM_USER0);
+	de = (struct ext2_dir_entry_2 *)kaddr;
 	de->name_len = 1;
 	de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1));
 	memcpy (de->name, ".\0\0", 4);
 	de->inode = cpu_to_le32(inode->i_ino);
 	ext2_set_de_type (de, inode);
 
-	de = (struct ext2_dir_entry_2 *) (base + EXT2_DIR_REC_LEN(1));
+	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
 	de->name_len = 2;
 	de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1));
 	de->inode = cpu_to_le32(parent->i_ino);
 	memcpy (de->name, "..\0", 4);
 	ext2_set_de_type (de, inode);
-
+	kunmap_atomic(kaddr, KM_USER0);
 	err = ext2_commit_chunk(page, 0, chunk_size);
 fail:
 	page_cache_release(page);

@@ -2200,8 +2200,9 @@ int page_symlink(struct inode *inode, co
 	err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
 	if (err)
 		goto fail_map;
-	kaddr = page_address(page);
+	kaddr = kmap_atomic(page, KM_USER0);
 	memcpy(kaddr, symname, len-1);
+	kunmap_atomic(kaddr, KM_USER0);
 	mapping->a_ops->commit_write(NULL, page, 0, len-1);
 	/*
 	 * Notice that we are _not_ going to block here - end of page is

@@ -210,8 +210,7 @@ do_lo_send(struct loop_device *lo, struc
 			goto fail;
 		if (aops->prepare_write(file, page, offset, offset+size))
 			goto unlock;
-		kaddr = page_address(page);
-		flush_dcache_page(page);
+		kaddr = kmap(page);
 		transfer_result = lo_do_transfer(lo, WRITE, kaddr + offset, data, size, IV);
 		if (transfer_result) {
 			/*

@@ -221,6 +220,8 @@ do_lo_send(struct loop_device *lo, struc
 			printk(KERN_ERR "loop: transfer error block %ld\n", index);
 			memset(kaddr + offset, 0, size);
 		}
+		flush_dcache_page(page);
+		kunmap(page);
 		if (aops->commit_write(file, page, offset, offset+size))
 			goto unlock;
 		if (transfer_result)

@@ -109,9 +109,11 @@ int rd_blocksize = BLOCK_SIZE;			/* bloc
 static int ramdisk_readpage(struct file *file, struct page * page)
 {
 	if (!PageUptodate(page)) {
-		memset(kmap(page), 0, PAGE_CACHE_SIZE);
-		kunmap(page);
+		void *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr, 0, PAGE_CACHE_SIZE);
 		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
 		SetPageUptodate(page);
 	}
 	unlock_page(page);

@@ -121,9 +123,11 @@ static int ramdisk_readpage(struct file 
 static int ramdisk_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
 {
 	if (!PageUptodate(page)) {
-		void *addr = page_address(page);
-		memset(addr, 0, PAGE_CACHE_SIZE);
+		void *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr, 0, PAGE_CACHE_SIZE);
 		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
 		SetPageUptodate(page);
 	}
 	SetPageDirty(page);

@@ -178,8 +182,11 @@ static int rd_blkdev_pagecache_IO(int rw
 			err = 0;
 
 			if (!PageUptodate(page)) {
-				memset(kmap(page), 0, PAGE_CACHE_SIZE);
-				kunmap(page);
+				void *kaddr = kmap_atomic(page, KM_USER0);
+
+				memset(kaddr, 0, PAGE_CACHE_SIZE);
+				flush_dcache_page(page);
+				kunmap_atomic(kaddr, KM_USER0);
 				SetPageUptodate(page);
 			}
 

@@ -27,6 +27,7 @@
 #include <linux/fs.h>
 #include <linux/amigaffs.h>
 #include <linux/mm.h>
+#include <linux/highmem.h>
 #include <linux/pagemap.h>
 #include <linux/buffer_head.h>
 

@@ -518,6 +519,7 @@ affs_do_readpage_ofs(struct file *file, 
 	pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
 	if (from > to || to > PAGE_CACHE_SIZE)
 		BUG();
+	kmap(page);
 	data = page_address(page);
 	bsize = AFFS_SB(sb)->s_data_blksize;
 	tmp = (page->index << PAGE_CACHE_SHIFT) + from;

@@ -537,6 +539,8 @@ affs_do_readpage_ofs(struct file *file, 
 		from += tmp;
 		boff = 0;
 	}
+	flush_dcache_page(page);
+	kunmap(page);
 	return 0;
 }
 

@@ -656,7 +660,11 @@ static int affs_prepare_write_ofs(struct
 			return err;
 	}
 	if (to < PAGE_CACHE_SIZE) {
-		memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
+		char *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
+		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
 		if (size > offset + to) {
 			if (size < offset + PAGE_CACHE_SIZE)
 				tmp = size & ~PAGE_CACHE_MASK;

@@ -59,9 +59,11 @@ static int mount_count = 0;
 static int driverfs_readpage(struct file *file, struct page * page)
 {
 	if (!PageUptodate(page)) {
-		memset(kmap(page), 0, PAGE_CACHE_SIZE);
-		kunmap(page);
+		void *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr, 0, PAGE_CACHE_SIZE);
 		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
 		SetPageUptodate(page);
 	}
 	unlock_page(page);

@@ -70,10 +72,12 @@ static int driverfs_readpage(struct file
 
 static int driverfs_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
 {
-	void *addr = kmap(page);
 	if (!PageUptodate(page)) {
-		memset(addr, 0, PAGE_CACHE_SIZE);
+		void *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr, 0, PAGE_CACHE_SIZE);
 		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
 		SetPageUptodate(page);
 	}
 	return 0;

@@ -85,7 +89,6 @@ static int driverfs_commit_write(struct 
 	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 
 	set_page_dirty(page);
-	kunmap(page);
 	if (pos > inode->i_size)
 		inode->i_size = pos;
 	return 0;

@@ -47,6 +47,7 @@
 #include <linux/stat.h>
 #include <linux/blkdev.h>
 #include <linux/quotaops.h>
+#include <linux/highmem.h>
 #include <linux/smp_lock.h>
 #include <asm/semaphore.h>
 #include <asm/byteorder.h>

@@ -751,7 +752,6 @@ jffs_do_readpage_nolock(struct file *fil
 
 	get_page(page);
 	/* Don't SetPageLocked(page), should be locked already */
-	buf = page_address(page);
 	ClearPageUptodate(page);
 	ClearPageError(page);
 

@@ -760,8 +760,10 @@ jffs_do_readpage_nolock(struct file *fil
 
 	read_len = 0;
 	result = 0;
-
 	offset = page->index << PAGE_CACHE_SHIFT;
+
+	kmap(page);
+	buf = page_address(page);
 	if (offset < inode->i_size) {
 		read_len = min_t(long, inode->i_size - offset, PAGE_SIZE);
 		r = jffs_read_data(f, buf, offset, read_len);

@@ -779,6 +781,8 @@ jffs_do_readpage_nolock(struct file *fil
 	/* This handles the case of partial or no read in above */
 	if(read_len < PAGE_SIZE)
 	        memset(buf + read_len, 0, PAGE_SIZE - read_len);
+	flush_dcache_page(page);
+	kunmap(page);
 
 	D3(printk (KERN_NOTICE "readpage(): up biglock\n"));
 	up(&c->fmc->biglock);

@@ -788,9 +792,8 @@ jffs_do_readpage_nolock(struct file *fil
 	}else {
 	        SetPageUptodate(page);	        
 	}
-	flush_dcache_page(page);
 
-	put_page(page);
+	page_cache_release(page);
 
 	D3(printk("jffs_readpage(): Leaving...\n"));
 

@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 #include <linux/time.h>
 #include <linux/pagemap.h>
+#include <linux/highmem.h>
 #include <linux/crc32.h>
 #include <linux/jffs2.h>
 #include "nodelist.h"

@@ -381,9 +382,10 @@ int jffs2_commit_write (struct file *fil
 	ri->isize = (uint32_t)inode->i_size;
 	ri->atime = ri->ctime = ri->mtime = CURRENT_TIME;
 
-	/* We rely on the fact that generic_file_write() currently kmaps the page for us. */
+	kmap(pg);
 	ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + start,
 				      (pg->index << PAGE_CACHE_SHIFT) + start, end - start, &writtenlen);
+	kunmap(pg);
 
 	if (ret) {
 		/* There was an error writing. */

@@ -459,7 +459,6 @@ static void __write_metapage(metapage_t 
 	if (rc) {
 		jERROR(1, ("prepare_write return %d!\n", rc));
 		ClearPageUptodate(mp->page);
-		kunmap(mp->page);
 		unlock_page(mp->page);
 		clear_bit(META_dirty, &mp->flag);
 		return;

@@ -7,6 +7,7 @@
  */
 
 #include "minix.h"
+#include <linux/highmem.h>
 #include <linux/smp_lock.h>
 
 typedef struct minix_dir_entry minix_dirent;

@@ -261,7 +262,7 @@ int minix_delete_entry(struct minix_dir_
 {
 	struct address_space *mapping = page->mapping;
 	struct inode *inode = (struct inode*)mapping->host;
-	char *kaddr = (char*)page_address(page);
+	char *kaddr = page_address(page);
 	unsigned from = (char*)de - kaddr;
 	unsigned to = from + minix_sb(inode->i_sb)->s_dirsize;
 	int err;

@@ -286,7 +287,7 @@ int minix_make_empty(struct inode *inode
 	struct page *page = grab_cache_page(mapping, 0);
 	struct minix_sb_info * sbi = minix_sb(inode->i_sb);
 	struct minix_dir_entry * de;
-	char *base;
+	char *kaddr;
 	int err;
 
 	if (!page)

@@ -297,15 +298,16 @@ int minix_make_empty(struct inode *inode
 		goto fail;
 	}
 
-	base = (char*)page_address(page);
-	memset(base, 0, PAGE_CACHE_SIZE);
+	kaddr = kmap_atomic(page, KM_USER0);
+	memset(kaddr, 0, PAGE_CACHE_SIZE);
 
-	de = (struct minix_dir_entry *) base;
+	de = (struct minix_dir_entry *)kaddr;
 	de->inode = inode->i_ino;
 	strcpy(de->name,".");
 	de = minix_next_entry(de, sbi);
 	de->inode = dir->i_ino;
 	strcpy(de->name,"..");
+	kunmap_atomic(kaddr, KM_USER0);
 
 	err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
 fail:

@@ -26,6 +26,7 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
+#include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/smp_lock.h>

@@ -47,8 +48,10 @@ static struct inode_operations ramfs_dir
 static int ramfs_readpage(struct file *file, struct page * page)
 {
 	if (!PageUptodate(page)) {
-		memset(kmap(page), 0, PAGE_CACHE_SIZE);
-		kunmap(page);
+		char *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr, 0, PAGE_CACHE_SIZE);
+		kunmap_atomic(kaddr, KM_USER0);
 		flush_dcache_page(page);
 		SetPageUptodate(page);
 	}

@@ -58,10 +61,12 @@ static int ramfs_readpage(struct file *f
 
 static int ramfs_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
 {
-	void *addr = kmap(page);
 	if (!PageUptodate(page)) {
-		memset(addr, 0, PAGE_CACHE_SIZE);
+		char *kaddr = kmap_atomic(page, KM_USER0);
+
+		memset(kaddr, 0, PAGE_CACHE_SIZE);
 		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
 		SetPageUptodate(page);
 	}
 	SetPageDirty(page);

@@ -73,7 +78,6 @@ static int ramfs_commit_write(struct fil
 	struct inode *inode = page->mapping->host;
 	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 
-	kunmap(page);
 	if (pos > inode->i_size)
 		inode->i_size = pos;
 	return 0;

@@ -7,6 +7,7 @@
 #include <linux/reiserfs_fs.h>
 #include <linux/smp_lock.h>
 #include <linux/pagemap.h>
+#include <linux/highmem.h>
 #include <asm/uaccess.h>
 #include <asm/unaligned.h>
 #include <linux/buffer_head.h>

@@ -1692,8 +1693,6 @@ static int grab_tail_page(struct inode *
     if (error)
 	goto unlock ;
 
-    kunmap(page) ; /* mapped by block_prepare_write */
-
     head = page_buffers(page) ;      
     bh = head;
     do {

@@ -1788,10 +1787,13 @@ void reiserfs_truncate_file(struct inode
         length = offset & (blocksize - 1) ;
 	/* if we are not on a block boundary */
 	if (length) {
+	    char *kaddr;
+
 	    length = blocksize - length ;
-	    memset((char *)kmap(page) + offset, 0, length) ;   
+	    kaddr = kmap_atomic(page, KM_USER0) ;
+	    memset(kaddr + offset, 0, length) ;   
 	    flush_dcache_page(page) ;
-	    kunmap(page) ;
+	    kunmap_atomic(kaddr, KM_USER0) ;
 	    if (buffer_mapped(bh) && bh->b_blocknr != 0) {
 	        mark_buffer_dirty(bh) ;
 	    }

@@ -1941,23 +1943,25 @@ static int reiserfs_write_full_page(stru
     struct buffer_head *arr[PAGE_CACHE_SIZE/512] ;
     int nr = 0 ;
 
-    if (!page_has_buffers(page)) {
+    if (!page_has_buffers(page))
         block_prepare_write(page, 0, 0, NULL) ;
-	kunmap(page) ;
-    }
+
     /* last page in the file, zero out any contents past the
     ** last byte in the file
     */
     if (page->index >= end_index) {
+	char *kaddr;
+
         last_offset = inode->i_size & (PAGE_CACHE_SIZE - 1) ;
 	/* no file contents in this page */
 	if (page->index >= end_index + 1 || !last_offset) {
 	    error =  -EIO ;
 	    goto fail ;
 	}
-	memset((char *)kmap(page)+last_offset, 0, PAGE_CACHE_SIZE-last_offset) ;
+	kaddr = kmap_atomic(page, KM_USER0);
+	memset(kaddr + last_offset, 0, PAGE_CACHE_SIZE-last_offset) ;
 	flush_dcache_page(page) ;
-	kunmap(page) ;
+	kunmap_atomic(kaddr, KM_USER0) ;
     }
     head = page_buffers(page) ;
     bh = head ;

@@ -14,6 +14,7 @@
  */
 
 #include <linux/pagemap.h>
+#include <linux/highmem.h>
 #include <linux/smp_lock.h>
 #include "sysv.h"
 

@@ -273,6 +274,7 @@ int sysv_make_empty(struct inode *inode,
 
 	if (!page)
 		return -ENOMEM;
+	kmap(page);
 	err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE);
 	if (err) {
 		unlock_page(page);

@@ -291,6 +293,7 @@ int sysv_make_empty(struct inode *inode,
 
 	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
 fail:
+	kunmap(page);
 	page_cache_release(page);
 	return err;
 }

@@ -982,11 +982,24 @@ static int fat_readpage(struct file *fil
 {
 	return block_read_full_page(page,fat_get_block);
 }
-static int fat_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
+
+static int
+fat_prepare_write(struct file *file, struct page *page,
+			unsigned from, unsigned to)
 {
+	kmap(page);
 	return cont_prepare_write(page,from,to,fat_get_block,
 		&MSDOS_I(page->mapping->host)->mmu_private);
 }
+
+static int
+fat_commit_write(struct file *file, struct page *page,
+			unsigned from, unsigned to)
+{
+	kunmap(page);
+	return generic_commit_write(file, page, from, to);
+}
+
 static int _fat_bmap(struct address_space *mapping, long block)
 {
 	return generic_block_bmap(mapping,block,fat_get_block);

@@ -996,7 +1009,7 @@ static struct address_space_operations f
 	writepage: fat_writepage,
 	sync_page: block_sync_page,
 	prepare_write: fat_prepare_write,
-	commit_write: generic_commit_write,
+	commit_write: fat_commit_write,
 	bmap: _fat_bmap
 };
 

@@ -1284,15 +1284,15 @@ int reiserfs_delete_item (struct reiserf
         **
         ** p_s_un_bh is from the page cache (all unformatted nodes are
         ** from the page cache) and might be a highmem page.  So, we
-        ** can't use p_s_un_bh->b_data.  But, the page has already been
-        ** kmapped, so we can use page_address()
+        ** can't use p_s_un_bh->b_data.
 	** -clm
 	*/
 
-        data = page_address(p_s_un_bh->b_page) ;
+        data = kmap_atomic(p_s_un_bh->b_page, KM_USER0);
 	off = ((le_ih_k_offset (&s_ih) - 1) & (PAGE_CACHE_SIZE - 1));
 	memcpy(data + off,
 	       B_I_PITEM(PATH_PLAST_BUFFER(p_s_path), &s_ih), n_ret_value);
+	kunmap_atomic(data, KM_USER0);
     }
 
     /* Perform balancing after all resources have been collected at once. */ 

@@ -122,11 +122,12 @@ int direct2indirect (struct reiserfs_tra
     }
     /* if we've copied bytes from disk into the page, we need to zero
     ** out the unused part of the block (it was not up to date before)
-    ** the page is still kmapped (by whoever called reiserfs_get_block)
     */
     if (up_to_date_bh) {
         unsigned pgoff = (tail_offset + total_tail - 1) & (PAGE_CACHE_SIZE - 1);
-	memset(page_address(unbh->b_page) + pgoff, 0, n_blk_size - total_tail) ;
+	char *kaddr=kmap_atomic(up_to_date_bh->b_page, KM_USER0);
+	memset(kaddr + pgoff, 0, n_blk_size - total_tail) ;
+	kunmap_atomic(kaddr, KM_USER0);
     }
 
     REISERFS_I(inode)->i_first_direct_byte = U32_MAX;