The patch titled
VFS: fix a race in lease-breaking during truncate
has been added to the -mm tree. Its filename is
vfs-fix-a-race-in-lease-breaking-during-truncate.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: VFS: fix a race in lease-breaking during truncate
From: david m. richter <richterd@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Signed-off-by: "J. Bruce Fields" <bfields@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/open.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff -puN fs/open.c~vfs-fix-a-race-in-lease-breaking-during-truncate fs/open.c
--- a/fs/open.c~vfs-fix-a-race-in-lease-breaking-during-truncate
+++ a/fs/open.c
@@ -256,24 +256,26 @@ static long do_sys_truncate(const char _
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:
_
Patches currently in -mm which might be from richterd@xxxxxxxxxxxxxx are
git-vfs-lease-api.patch
vfs-fix-a-race-in-lease-breaking-during-truncate.patch
-
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