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authorAl Viro <viro@zeniv.linux.org.uk>2010-06-06 23:49:18 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2010-08-09 16:48:15 -0400
commitf8ad850f11e11d10e7de1a16ca53cb193afc9313 (patch)
tree4812193c6be29f41d3de3ae74705e95a9566546c /fs/hostfs/hostfs_user.c
parentf8d7e1877e5121841bc9a4d284a04dbc13f45bea (diff)
try to get rid of races in hostfs open()
In case of mode mismatch, do *not* blindly close the descriptor another openers might be using right now. Open the underlying file with currently sufficient mode, then * if current mode has grown so that it's sufficient for us now, just close our new fd * if current mode has grown and our fd is *not* enough to cover it, close and repeat. * otherwise, install our fd if the file hadn't been opened at all or dup2() our fd over the current one (and close our fd). Critical section is protected by mutex; yes, system-wide. All we do under it is a bunch of comparison and maybe an overwriting dup2() on host. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/hostfs/hostfs_user.c')
-rw-r--r--fs/hostfs/hostfs_user.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c
index 91ebfcefa40..6777aa06ce2 100644
--- a/fs/hostfs/hostfs_user.c
+++ b/fs/hostfs/hostfs_user.c
@@ -160,6 +160,11 @@ int fsync_file(int fd, int datasync)
return 0;
}
+int replace_file(int oldfd, int fd)
+{
+ return dup2(oldfd, fd);
+}
+
void close_file(void *stream)
{
close(*((int *) stream));