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NTFS: Fix a mount time deadlock.

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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 <aia21@cantab.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Anton Altaparmakov
2007-10-12 09:37:15 +01:00
committed by Linus Torvalds
parent f26e51f67a
commit bfab36e816
9 changed files with 181 additions and 53 deletions
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36
fs/ntfs/file.c
View File

@@ -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);