NTFS: 2.0.17 - Cleanups and optimizations - shrinking the ToDo list.

- Modify fs/ntfs/inode.c::ntfs_read_locked_inode() to return an error
  code and update callers, i.e. ntfs_iget(), to pass that error code
  up instead of just using -EIO.
- Modifications to super.c to ensure that both mount and remount
  cannot set any write related options when the driver is compiled
  read-only.
- Optimize block resolution in fs/ntfs/aops.c::ntfs_read_block() to
  cache the current run list element. This should improve performance
  when reading very large and/or very fragmented data.

Documentation/filesystems/ntfs.txt

@@ -247,6 +247,8 @@ ChangeLog
 
 Note, a technical ChangeLog aimed at kernel hackers is in fs/ntfs/ChangeLog.
 
+2.0.17:
+	- Cleanups and optimizations.
 2.0.16:
 	- Fix stupid bug introduced in 2.0.15 in new attribute inode API.
 	- Big internal cleanup replacing the mftbmp access hacks by using the

fs/ntfs/ChangeLog

@@ -9,21 +9,23 @@ ToDo:
 	  read() will fail when s_maxbytes is reached? -> Investigate this.
 	- Implement/allow non-resident index bitmaps in dir.c::ntfs_readdir()
 	  and then also consider initialized_size w.r.t. the bitmaps, etc.
-	- vcn_to_lcn() should somehow return the correct pointer within the
-	  ->run_list so we can get at the lcns for the following vcns, this is
-	  strictly a speed optimization. Obviously need to keep the ->run_list
-	  locked or RACE. load_attribute_list() already performs such an
-	  optimization so use the same optimization where desired.
 	- Consider if ntfs_file_read_compressed_block() shouldn't be coping
 	  with initialized_size < data_size. I don't think it can happen but
 	  it requires more careful consideration.
-	- CLEANUP: Modularising code in aops.c a bit, e.g. a-la get_block(),
-	  will be cleaner and make code reuse easier.
-	- Modify ntfs_read_locked_inode() to return an error code and update
-	  callers, i.e. ntfs_iget(), to pass that error code up instead of just
-	  using -EIO.
 	- Enable NFS exporting of NTFS.
 
+2.0.17 - Cleanups and optimizations - shrinking the ToDo list.
+
+	- Modify fs/ntfs/inode.c::ntfs_read_locked_inode() to return an error
+	  code and update callers, i.e. ntfs_iget(), to pass that error code
+	  up instead of just using -EIO.
+	- Modifications to super.c to ensure that both mount and remount
+	  cannot set any write related options when the driver is compiled
+	  read-only.
+	- Optimize block resolution in fs/ntfs/aops.c::ntfs_read_block() to
+	  cache the current run list element. This should improve performance
+	  when reading very large and/or very fragmented data.
+
 2.0.16 - Convert access to $MFT/$BITMAP to attribute inode API.
 
 	- Fix a stupid bug introduced in 2.0.15 where we were unmapping the

fs/ntfs/Makefile

@@ -5,11 +5,15 @@ obj-$(CONFIG_NTFS_FS) += ntfs.o
 ntfs-objs := aops.o attrib.o compress.o debug.o dir.o file.o inode.o mft.o \
 	     mst.o namei.o super.o sysctl.o time.o unistr.o upcase.o
 
-EXTRA_CFLAGS = -DNTFS_VERSION=\"2.0.16\"
+EXTRA_CFLAGS = -DNTFS_VERSION=\"2.0.17\"
 
 ifeq ($(CONFIG_NTFS_DEBUG),y)
 EXTRA_CFLAGS += -DDEBUG
 endif
 
+#ifeq ($(CONFIG_NTFS_RW),y)
+#EXTRA_CFLAGS += -DNTFS_RW
+#endif
+
 include $(TOPDIR)/Rules.make
 

fs/ntfs/aops.c

@@ -162,6 +162,7 @@ static int ntfs_read_block(struct page *page)
 	LCN lcn;
 	ntfs_inode *ni;
 	ntfs_volume *vol;
+	run_list_element *rl;
 	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 	sector_t iblock, lblock, zblock;
 	unsigned int blocksize, blocks, vcn_ofs;
@@ -192,6 +193,7 @@ static int ntfs_read_block(struct page *page)
 #endif
 
 	/* Loop through all the buffers in the page. */
+	rl = NULL;
 	nr = i = 0;
 	do {
 		if (unlikely(buffer_uptodate(bh)))
@@ -210,11 +212,18 @@ static int ntfs_read_block(struct page *page)
 					vol->cluster_size_bits;
 			vcn_ofs = ((VCN)iblock << blocksize_bits) &
 					vol->cluster_size_mask;
-retry_remap:
-			/* Convert the vcn to the corresponding lcn. */
-			down_read(&ni->run_list.lock);
-			lcn = vcn_to_lcn(ni->run_list.rl, vcn);
-			up_read(&ni->run_list.lock);
+			if (!rl) {
+lock_retry_remap:
+				down_read(&ni->run_list.lock);
+				rl = ni->run_list.rl;
+			}
+			if (likely(rl != NULL)) {
+				/* Seek to element containing target vcn. */
+				while (rl->length && rl[1].vcn <= vcn)
+					rl++;
+				lcn = vcn_to_lcn(rl, vcn);
+			} else
+				lcn = (LCN)LCN_RL_NOT_MAPPED;
 			/* Successful remap. */
 			if (lcn >= 0) {
 				/* Setup buffer head to correct block. */
@@ -235,8 +244,14 @@ static int ntfs_read_block(struct page *page)
 			/* If first try and run list unmapped, map and retry. */
 			if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
 				is_retry = TRUE;
+				/*
+				 * Attempt to map run list, dropping lock for
+				 * the duration.
+				 */
+				up_read(&ni->run_list.lock);
 				if (!map_run_list(ni, vcn))
-					goto retry_remap;
+					goto lock_retry_remap;
+				rl = NULL;
 			}
 			/* Hard error, zero out region. */
 			SetPageError(page);
@@ -261,6 +276,10 @@ static int ntfs_read_block(struct page *page)
 		set_buffer_uptodate(bh);
 	} while (i++, iblock++, (bh = bh->b_this_page) != head);
 
+	/* Release the lock if we took it. */
+	if (rl)
+		up_read(&ni->run_list.lock);
+
 	/* Check we have at least one buffer ready for i/o. */
 	if (nr) {
 		/* Lock the buffers. */

fs/ntfs/attrib.c

@@ -964,7 +964,7 @@ int map_run_list(ntfs_inode *ni, VCN vcn)
 	}
 
 	down_write(&ni->run_list.lock);
-	/* Make sure someone else didn't do the work while we were spinning. */
+	/* Make sure someone else didn't do the work while we were sleeping. */
 	if (likely(vcn_to_lcn(ni->run_list.rl, vcn) <= LCN_RL_NOT_MAPPED)) {
 		run_list_element *rl;
 

fs/ntfs/super.c

@@ -323,6 +323,11 @@ static int ntfs_remount(struct super_block *sb, int *flags, char *opt)
 
 	if (!parse_options(vol, opt))
 		return -EINVAL;
+
+#ifndef NTFS_RW
+	*flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
+#endif
+
 	return 0;
 }
 
@@ -789,9 +794,6 @@ static BOOL load_system_files(ntfs_volume *vol)
 		ntfs_error(sb, "Failed to load $MFT/$BITMAP attribute.");
 		return FALSE;
 	}
-	// FIXME: If mounting read-only, it would be ok to ignore errors when
-	// loading the mftbmp but we then need to make sure nobody remounts the
-	// volume read-write...
 
 	/* Get mft mirror inode. */
 	vol->mftmirr_ino = ntfs_iget(sb, FILE_MFTMirr);
@@ -858,8 +860,8 @@ static BOOL load_system_files(ntfs_volume *vol)
 			le16_to_cpu(ctx->attr->_ARA(value_offset)));
 	/* Some bounds checks. */
 	if ((u8*)vi < (u8*)ctx->attr || (u8*)vi +
-			le32_to_cpu(ctx->attr->_ARA(value_length)) > (u8*)ctx->attr +
-			le32_to_cpu(ctx->attr->length))
+			le32_to_cpu(ctx->attr->_ARA(value_length)) >
+			(u8*)ctx->attr + le32_to_cpu(ctx->attr->length))
 		goto err_put_vol;
 	/* Setup volume flags and version. */
 	vol->vol_flags = vi->flags;
@@ -1306,6 +1308,9 @@ static int ntfs_fill_super(struct super_block *sb, void *opt, const int silent)
 	int result;
 
 	ntfs_debug("Entering.");
+#ifndef NTFS_RW
+	sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
+#endif
 	/* Allocate a new ntfs_volume and place it in sb->u.generic_sbp. */
 	sb->u.generic_sbp = kmalloc(sizeof(ntfs_volume), GFP_NOFS);
 	vol = NTFS_SB(sb);
@@ -1346,9 +1351,6 @@ static int ntfs_fill_super(struct super_block *sb, void *opt, const int silent)
 	if (!parse_options(vol, (char*)opt))
 		goto err_out_now;
 
-	/* We are just a read-only fs at the moment. */
-	sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
-
 	/*
 	 * TODO: Fail safety check. In the future we should really be able to
 	 * cope with this being the case, but for now just bail out.
@@ -1623,7 +1625,7 @@ static int __init init_ntfs_fs(void)
 
 	/* This may be ugly but it results in pretty output so who cares. (-8 */
 	printk(KERN_INFO "NTFS driver " NTFS_VERSION " [Flags: R/"
-#ifdef CONFIG_NTFS_RW
+#ifdef NTFS_RW
 			"W"
 #else
 			"O"