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authorAnton Altaparmakov <aia21@cam.ac.uk>2007-11-03 07:38:59 +0000
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-03 12:27:21 -0700
commitebab89909e0dc716282d5e7f6e73a3155fe66d4a (patch)
tree8cee9ff6f9e0a08c6f08853e38e563514e92a99e /fs/ntfs/aops.c
parent74521c28e550c4ec265cda14114bd9b908e9de34 (diff)
downloadlinux-ebab89909e0dc716282d5e7f6e73a3155fe66d4a.tar.gz
NTFS: Fix read regression.
The regression was caused by:
        commit[a32ea1e1f925399e0d81ca3f7394a44a6dafa12c] Fix read/truncate race

This causes ntfs_readpage() to be called for a zero i_size inode, which
failed when the file was compressed and non-resident.

Thanks a lot to Mike Galbraith for reporting the issue and tracking down
the commit that caused the regression.

Looking into it I found three bugs which the patch fixes.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Tested-by:  Mike Galbraith <efault@gmx.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ntfs/aops.c')
-rw-r--r--fs/ntfs/aops.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index cfdc7900d271..ad87cb01299b 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -405,6 +405,15 @@ static int ntfs_readpage(struct file *file, struct page *page)
 
 retry_readpage:
 	BUG_ON(!PageLocked(page));
+	vi = page->mapping->host;
+	i_size = i_size_read(vi);
+	/* Is the page fully outside i_size? (truncate in progress) */
+	if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
+			PAGE_CACHE_SHIFT)) {
+		zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
+		ntfs_debug("Read outside i_size - truncated?");
+		goto done;
+	}
 	/*
 	 * This can potentially happen because we clear PageUptodate() during
 	 * ntfs_writepage() of MstProtected() attributes.
@@ -413,7 +422,6 @@ retry_readpage:
 		unlock_page(page);
 		return 0;
 	}
-	vi = page->mapping->host;
 	ni = NTFS_I(vi);
 	/*
 	 * Only $DATA attributes can be encrypted and only unnamed $DATA