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authorAnton Altaparmakov <aia21@cam.ac.uk>2007-10-12 09:37:15 +0100
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-12 09:16:30 -0700
commitbfab36e81611e60573b84eb4e4b4c8d8545b2320 (patch)
treeacd151a4c85459dcd2f6575ceb385090ebaaf984 /fs/ntfs/attrib.c
parentf26e51f67ae6a75ffc57b96cf5fe096f75e778cb (diff)
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>
Diffstat (limited to 'fs/ntfs/attrib.c')
-rw-r--r--fs/ntfs/attrib.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 1c08fefe487..92dabdcf2b8 100644
--- a/fs/ntfs/attrib.c
+++ b/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.");