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 <aia21@cantab.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 11 deletions

diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 6e5c2534f4bc..cfdc7900d271 100644
--- a/fs/ntfs/aops.c
+++ b/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 @@ retry_readpage:
                 /* 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 @@ retry_writepage:
                 /* 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. */