NTFS: Fix a mount time deadlock.

Big thanks go to Mathias Kolehmainen for reporting the bug, providing
debug output and testing the patches I sent him to get it working.

The fix was to stop calling ntfs_attr_set() at mount time as that causes
balance_dirty_pages_ratelimited() to be called which on systems with
little memory actually tries to go and balance the dirty pages which tries
to take the s_umount semaphore but because we are still in fill_super()
across which the VFS holds s_umount for writing this results in a
deadlock.

We now do the dirty work by hand by submitting individual buffers.  This
has the annoying "feature" that mounting can take a few seconds if the
journal is large as we have clear it all.  One day someone should improve
on this by deferring the journal clearing to a helper kernel thread so it
can be done in the background but I don't have time for this at the moment
and the current solution works fine so I am leaving it like this for now.

Signed-off-by: Anton Altaparmakov <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Documentation/filesystems/ntfs.txt

@@ -407,7 +407,7 @@ raiddev /dev/md0
 	device		/dev/hda5
 	raid-disk	0
 	device		/dev/hdb1
-	raid-disl	1
+	raid-disk	1
 
 For linear raid, just change the raid-level above to "raid-level linear", for
 mirrors, change it to "raid-level 1", and for stripe sets with parity, change
@@ -457,6 +457,8 @@ ChangeLog
 
 Note, a technical ChangeLog aimed at kernel hackers is in fs/ntfs/ChangeLog.
 
+2.1.29:
+	- Fix a deadlock when mounting read-write.
 2.1.28:
 	- Fix a deadlock.
 2.1.27:

fs/ntfs/ChangeLog

@@ -17,6 +17,18 @@ ToDo/Notes:
 	  happen is unclear however so it is worth waiting until someone hits
 	  the problem.
 
+2.1.29 - Fix a deadlock at mount time.
+
+	- During mount the VFS holds s_umount lock on the superblock.  So when
+	  we try to empty the journal $LogFile contents by calling
+	  ntfs_attr_set() when the machine does not have much memory and the
+	  journal is large ntfs_attr_set() results in the VM trying to balance
+	  dirty pages which in turn tries to that the s_umount lock and thus we
+	  get a deadlock.  The solution is to not use ntfs_attr_set() and
+	  instead do the zeroing by hand at the block level rather than page
+	  cache level.
+	- Fix sparse warnings.
+
 2.1.28 - Fix a deadlock.
 
 	- Fix deadlock in fs/ntfs/inode.c::ntfs_put_inode().  Thanks to Sergey

fs/ntfs/Makefile

@@ -6,7 +6,7 @@ ntfs-objs := aops.o attrib.o collate.o compress.o debug.o dir.o file.o \
 	     index.o inode.o mft.o mst.o namei.o runlist.o super.o sysctl.o \
 	     unistr.o upcase.o
 
-EXTRA_CFLAGS = -DNTFS_VERSION=\"2.1.28\"
+EXTRA_CFLAGS = -DNTFS_VERSION=\"2.1.29\"
 
 ifeq ($(CONFIG_NTFS_DEBUG),y)
 EXTRA_CFLAGS += -DDEBUG

fs/ntfs/aops.c

@@ -2,7 +2,7 @@
  * aops.c - NTFS kernel address space operations and page cache handling.
  *	    Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -396,7 +396,7 @@ static int ntfs_readpage(struct file *file, struct page *page)
 	loff_t i_size;
 	struct inode *vi;
 	ntfs_inode *ni, *base_ni;
-	u8 *kaddr;
+	u8 *addr;
 	ntfs_attr_search_ctx *ctx;
 	MFT_RECORD *mrec;
 	unsigned long flags;
@@ -491,15 +491,15 @@ static int ntfs_readpage(struct file *file, struct page *page)
 		/* Race with shrinking truncate. */
 		attr_len = i_size;
 	}
-	kaddr = kmap_atomic(page, KM_USER0);
+	addr = kmap_atomic(page, KM_USER0);
 	/* Copy the data to the page. */
-	memcpy(kaddr, (u8*)ctx->attr +
+	memcpy(addr, (u8*)ctx->attr +
 			le16_to_cpu(ctx->attr->data.resident.value_offset),
 			attr_len);
 	/* Zero the remainder of the page. */
-	memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+	memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
 	flush_dcache_page(page);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(addr, KM_USER0);
 put_unm_err_out:
 	ntfs_attr_put_search_ctx(ctx);
 unm_err_out:
@@ -1344,7 +1344,7 @@ static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
 	loff_t i_size;
 	struct inode *vi = page->mapping->host;
 	ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
-	char *kaddr;
+	char *addr;
 	ntfs_attr_search_ctx *ctx = NULL;
 	MFT_RECORD *m = NULL;
 	u32 attr_len;
@@ -1484,14 +1484,14 @@ static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
 		/* Shrinking cannot fail. */
 		BUG_ON(err);
 	}
-	kaddr = kmap_atomic(page, KM_USER0);
+	addr = kmap_atomic(page, KM_USER0);
 	/* Copy the data from the page to the mft record. */
 	memcpy((u8*)ctx->attr +
 			le16_to_cpu(ctx->attr->data.resident.value_offset),
-			kaddr, attr_len);
+			addr, attr_len);
 	/* Zero out of bounds area in the page cache page. */
-	memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
-	kunmap_atomic(kaddr, KM_USER0);
+	memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+	kunmap_atomic(addr, KM_USER0);
 	flush_dcache_page(page);
 	flush_dcache_mft_record_page(ctx->ntfs_ino);
 	/* We are done with the page. */

fs/ntfs/attrib.c

@@ -1,7 +1,7 @@
 /**
  * attrib.c - NTFS attribute operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -2500,7 +2500,7 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
 	struct page *page;
 	u8 *kaddr;
 	pgoff_t idx, end;
-	unsigned int start_ofs, end_ofs, size;
+	unsigned start_ofs, end_ofs, size;
 
 	ntfs_debug("Entering for ofs 0x%llx, cnt 0x%llx, val 0x%hx.",
 			(long long)ofs, (long long)cnt, val);
@@ -2548,6 +2548,8 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
 		kunmap_atomic(kaddr, KM_USER0);
 		set_page_dirty(page);
 		page_cache_release(page);
+		balance_dirty_pages_ratelimited(mapping);
+		cond_resched();
 		if (idx == end)
 			goto done;
 		idx++;
@@ -2604,6 +2606,8 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
 		kunmap_atomic(kaddr, KM_USER0);
 		set_page_dirty(page);
 		page_cache_release(page);
+		balance_dirty_pages_ratelimited(mapping);
+		cond_resched();
 	}
 done:
 	ntfs_debug("Done.");

fs/ntfs/file.c

@@ -1,7 +1,7 @@
 /*
  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
@@ -26,7 +26,6 @@
 #include <linux/swap.h>
 #include <linux/uio.h>
 #include <linux/writeback.h>
-#include <linux/sched.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
@@ -362,7 +361,7 @@ static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
 	volatile char c;
 
 	/* Set @end to the first byte outside the last page we care about. */
-	end = (const char __user*)PAGE_ALIGN((ptrdiff_t __user)uaddr + bytes);
+	end = (const char __user*)PAGE_ALIGN((unsigned long)uaddr + bytes);
 
 	while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
 		;
@@ -532,7 +531,8 @@ static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
 	blocksize_bits = vol->sb->s_blocksize_bits;
 	u = 0;
 	do {
-		struct page *page = pages[u];
+		page = pages[u];
+		BUG_ON(!page);
 		/*
 		 * create_empty_buffers() will create uptodate/dirty buffers if
 		 * the page is uptodate/dirty.
@@ -1291,7 +1291,7 @@ static inline size_t ntfs_copy_from_user(struct page **pages,
 		size_t bytes)
 {
 	struct page **last_page = pages + nr_pages;
-	char *kaddr;
+	char *addr;
 	size_t total = 0;
 	unsigned len;
 	int left;
@@ -1300,13 +1300,13 @@ static inline size_t ntfs_copy_from_user(struct page **pages,
 		len = PAGE_CACHE_SIZE - ofs;
 		if (len > bytes)
 			len = bytes;
-		kaddr = kmap_atomic(*pages, KM_USER0);
-		left = __copy_from_user_inatomic(kaddr + ofs, buf, len);
-		kunmap_atomic(kaddr, KM_USER0);
+		addr = kmap_atomic(*pages, KM_USER0);
+		left = __copy_from_user_inatomic(addr + ofs, buf, len);
+		kunmap_atomic(addr, KM_USER0);
 		if (unlikely(left)) {
 			/* Do it the slow way. */
-			kaddr = kmap(*pages);
-			left = __copy_from_user(kaddr + ofs, buf, len);
+			addr = kmap(*pages);
+			left = __copy_from_user(addr + ofs, buf, len);
 			kunmap(*pages);
 			if (unlikely(left))
 				goto err_out;
@@ -1408,26 +1408,26 @@ static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
 		size_t *iov_ofs, size_t bytes)
 {
 	struct page **last_page = pages + nr_pages;
-	char *kaddr;
+	char *addr;
 	size_t copied, len, total = 0;
 
 	do {
 		len = PAGE_CACHE_SIZE - ofs;
 		if (len > bytes)
 			len = bytes;
-		kaddr = kmap_atomic(*pages, KM_USER0);
-		copied = __ntfs_copy_from_user_iovec_inatomic(kaddr + ofs,
+		addr = kmap_atomic(*pages, KM_USER0);
+		copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
 				*iov, *iov_ofs, len);
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(addr, KM_USER0);
 		if (unlikely(copied != len)) {
 			/* Do it the slow way. */
-			kaddr = kmap(*pages);
-			copied = __ntfs_copy_from_user_iovec_inatomic(kaddr + ofs,
+			addr = kmap(*pages);
+			copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
 					*iov, *iov_ofs, len);
 			/*
 			 * Zero the rest of the target like __copy_from_user().
 			 */
-			memset(kaddr + ofs + copied, 0, len - copied);
+			memset(addr + ofs + copied, 0, len - copied);
 			kunmap(*pages);
 			if (unlikely(copied != len))
 				goto err_out;
@@ -1735,8 +1735,6 @@ static int ntfs_commit_pages_after_write(struct page **pages,
 	read_unlock_irqrestore(&ni->size_lock, flags);
 	BUG_ON(initialized_size != i_size);
 	if (end > initialized_size) {
-		unsigned long flags;
-
 		write_lock_irqsave(&ni->size_lock, flags);
 		ni->initialized_size = end;
 		i_size_write(vi, end);

fs/ntfs/inode.c

@@ -34,7 +34,6 @@
 #include "dir.h"
 #include "debug.h"
 #include "inode.h"
-#include "attrib.h"
 #include "lcnalloc.h"
 #include "malloc.h"
 #include "mft.h"
@@ -2500,8 +2499,6 @@ int ntfs_truncate(struct inode *vi)
 	/* Resize the attribute record to best fit the new attribute size. */
 	if (new_size < vol->mft_record_size &&
 			!ntfs_resident_attr_value_resize(m, a, new_size)) {
-		unsigned long flags;
-
 		/* The resize succeeded! */
 		flush_dcache_mft_record_page(ctx->ntfs_ino);
 		mark_mft_record_dirty(ctx->ntfs_ino);