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authordavid m. richter <richterd@citi.umich.edu>2007-07-31 00:39:12 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-31 15:39:42 -0700
commit9700382c3c9ff3e673e587084d76eedb3ba88668 (patch)
tree57ed58d87e765323692e463c8b7ee64f702dff0d /fs/open.c
parent937472b00b666ecbf1464502f857ec63b024af72 (diff)
downloadlwn-9700382c3c9ff3e673e587084d76eedb3ba88668.tar.gz
lwn-9700382c3c9ff3e673e587084d76eedb3ba88668.zip
VFS: fix a race in lease-breaking during truncate
It is possible that another process could acquire a new file lease right after break_lease() is called during a truncate, but before lease-granting is disabled by the subsequent get_write_access(). Merely switching the order of the break_lease() and get_write_access() calls prevents this race. Signed-off-by: David M. Richter <richterd@citi.umich.edu> Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/open.c')
-rw-r--r--fs/open.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/fs/open.c b/fs/open.c
index e27c205364d3..1d9e5e98bf4e 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -256,24 +256,26 @@ static long do_sys_truncate(const char __user * path, loff_t length)
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto dput_and_out;
- /*
- * Make sure that there are no leases.
- */
- error = break_lease(inode, FMODE_WRITE);
+ error = get_write_access(inode);
if (error)
goto dput_and_out;
- error = get_write_access(inode);
+ /*
+ * Make sure that there are no leases. get_write_access() protects
+ * against the truncate racing with a lease-granting setlease().
+ */
+ error = break_lease(inode, FMODE_WRITE);
if (error)
- goto dput_and_out;
+ goto put_write_and_out;
error = locks_verify_truncate(inode, NULL, length);
if (!error) {
DQUOT_INIT(inode);
error = do_truncate(nd.dentry, length, 0, NULL);
}
- put_write_access(inode);
+put_write_and_out:
+ put_write_access(inode);
dput_and_out:
path_release(&nd);
out: