From 8a22efa15b46d524577cac79da63cebca8e8307f Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 9 Mar 2018 15:51:02 +0200 Subject: ovl: do not try to reconnect a disconnected origin dentry On lookup of non directory, we try to decode the origin file handle stored in upper inode. The origin file handle is supposed to be decoded to a disconnected non-dir dentry, which is fine, because we only need the lower inode of a copy up origin. However, if the origin file handle somehow turns out to be a directory we pay the expensive cost of reconnecting the directory dentry, only to get a mismatch file type and drop the dentry. Optimize this case by explicitly opting out of reconnecting the dentry. Opting-out of reconnect is done by passing a NULL acceptable callback to exportfs_decode_fh(). While the case described above is a strange corner case that does not really need to be optimized, the API added for this optimization will be used by a following patch to optimize a more common case of decoding an overlayfs file handle. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/namei.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'fs/overlayfs/namei.c') diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 24bd387321d1..810a333d2221 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -180,7 +180,8 @@ invalid: goto out; } -struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt) +struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt, + bool connected) { struct dentry *real; int bytes; @@ -195,7 +196,7 @@ struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt) bytes = (fh->len - offsetof(struct ovl_fh, fid)); real = exportfs_decode_fh(mnt, (struct fid *)fh->fid, bytes >> 2, (int)fh->type, - ovl_acceptable, mnt); + connected ? ovl_acceptable : NULL, mnt); if (IS_ERR(real)) { /* * Treat stale file handle to lower file as "origin unknown". @@ -319,14 +320,15 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, } -int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, +int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected, struct dentry *upperdentry, struct ovl_path **stackp) { struct dentry *origin = NULL; int i; for (i = 0; i < ofs->numlower; i++) { - origin = ovl_decode_real_fh(fh, ofs->lower_layers[i].mnt); + origin = ovl_decode_real_fh(fh, ofs->lower_layers[i].mnt, + connected); if (origin) break; } @@ -370,7 +372,7 @@ static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry, if (IS_ERR_OR_NULL(fh)) return PTR_ERR(fh); - err = ovl_check_origin_fh(ofs, fh, upperdentry, stackp); + err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp); kfree(fh); if (err) { @@ -460,7 +462,7 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index) if (IS_ERR_OR_NULL(fh)) return ERR_CAST(fh); - upper = ovl_decode_real_fh(fh, ofs->upper_mnt); + upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true); kfree(fh); if (IS_ERR_OR_NULL(upper)) @@ -567,7 +569,7 @@ int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index) /* Check if non-dir index is orphan and don't warn before cleaning it */ if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) { - err = ovl_check_origin_fh(ofs, fh, index, &stack); + err = ovl_check_origin_fh(ofs, fh, false, index, &stack); if (err) goto fail; -- cgit v1.2.3