Truncate the xattr znode when updating existing attributes.

If the attribute's new value was shorter than the old one the old
code would leave parts of the old value in the xattr znode.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #203

diff --git a/module/zfs/zpl_xattr.c b/module/zfs/zpl_xattr.c
index 82787cb..bb93414 100644 (file)
--- a/module/zfs/zpl_xattr.c
+++ b/module/zfs/zpl_xattr.c
@@ -191,6 +191,7 @@ zpl_xattr_set(struct inode *ip, const char *name, const void *value,
        cred_t *cr = CRED();
        ssize_t wrote;
        int error;
+       const int xattr_mode = S_IFREG | 0644;
 
        crhold(cr);
 
@@ -230,7 +231,7 @@ zpl_xattr_set(struct inode *ip, const char *name, const void *value,
        /* Lookup failed create a new xattr. */
        if (xip == NULL) {
                vap = kmem_zalloc(sizeof(vattr_t), KM_SLEEP);
-               vap->va_mode = S_IFREG | 0644;
+               vap->va_mode = xattr_mode;
                vap->va_mask = ATTR_MODE;
                vap->va_uid = crgetfsuid(cr);
                vap->va_gid = crgetfsgid(cr);
@@ -242,6 +243,11 @@ zpl_xattr_set(struct inode *ip, const char *name, const void *value,
        }
 
        ASSERT(xip != NULL);
+
+       error = -zfs_freesp(ITOZ(xip), 0, 0, xattr_mode, TRUE);
+       if (error)
+               goto out;
+
        wrote = zpl_write_common(xip, value, size, 0, UIO_SYSSPACE, 0, cr);
        if (wrote < 0)
                error = wrote;