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authorMiklos Szeredi <mszeredi@redhat.com>2016-06-29 16:03:55 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2016-06-29 16:03:55 +0200
commit03bea60409328de54e4ff7ec41672e12a9cb0908 (patch)
treee63b692eeb24c559c1e9b56369b18751a7bb9d5f /fs
parenta4859d75944a726533ab86d24bb5ffd1b2b7d6cc (diff)
downloadlinux-03bea60409328de54e4ff7ec41672e12a9cb0908.tar.gz
ovl: get_write_access() in truncate
When truncating a file we should check write access on the underlying inode. And we should do so on the lower file as well (before copy-up) for consistency. Original patch and test case by Aihua Zhang. - - >o >o - - test.c - - >o >o - - #include <stdio.h> #include <errno.h> #include <unistd.h> int main(int argc, char *argv[]) { int ret; ret = truncate(argv[0], 4096); if (ret != -1) { fprintf(stderr, "truncate(argv[0]) should have failed\n"); return 1; } if (errno != ETXTBSY) { perror("truncate(argv[0])"); return 1; } return 0; } - - >o >o - - >o >o - - >o >o - - Reported-by: Aihua Zhang <zhangaihua1@huawei.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Cc: <stable@vger.kernel.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/overlayfs/inode.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 8514d692042b..c831c2e5f803 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -59,16 +59,37 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
if (err)
goto out;
+ if (attr->ia_valid & ATTR_SIZE) {
+ struct inode *realinode = d_inode(ovl_dentry_real(dentry));
+
+ err = -ETXTBSY;
+ if (atomic_read(&realinode->i_writecount) < 0)
+ goto out_drop_write;
+ }
+
err = ovl_copy_up(dentry);
if (!err) {
+ struct inode *winode = NULL;
+
upperdentry = ovl_dentry_upper(dentry);
+ if (attr->ia_valid & ATTR_SIZE) {
+ winode = d_inode(upperdentry);
+ err = get_write_access(winode);
+ if (err)
+ goto out_drop_write;
+ }
+
inode_lock(upperdentry->d_inode);
err = notify_change(upperdentry, attr, NULL);
if (!err)
ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
inode_unlock(upperdentry->d_inode);
+
+ if (winode)
+ put_write_access(winode);
}
+out_drop_write:
ovl_drop_write(dentry);
out:
return err;