From cad218ab3320789ea4621c15e56b8114a4160bab Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 20 Feb 2020 09:00:19 +0200 Subject: ovl: check if upper fs supports RENAME_WHITEOUT As with other required upper fs features, we only warn if support is missing to avoid breaking existing sub-optimal setups. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/dir.c | 2 +- fs/overlayfs/overlayfs.h | 1 + fs/overlayfs/super.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 71 insertions(+), 1 deletion(-) (limited to 'fs/overlayfs') diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index b3471ef51440..c91b5aae8e32 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -42,7 +42,7 @@ int ovl_cleanup(struct inode *wdir, struct dentry *wdentry) return err; } -static struct dentry *ovl_lookup_temp(struct dentry *workdir) +struct dentry *ovl_lookup_temp(struct dentry *workdir) { struct dentry *temp; char name[20]; diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 70d17040ab4d..ea531b1075f2 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -453,6 +453,7 @@ struct ovl_cattr { struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, struct ovl_cattr *attr); int ovl_cleanup(struct inode *dir, struct dentry *dentry); +struct dentry *ovl_lookup_temp(struct dentry *workdir); struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr); /* file.c */ diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index e8965fd1a608..b6ecaf95db9f 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1071,6 +1071,66 @@ out: return err; } +/* + * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and + * negative values if error is encountered. + */ +static int ovl_check_rename_whiteout(struct dentry *workdir) +{ + struct inode *dir = d_inode(workdir); + struct dentry *temp; + struct dentry *dest; + struct dentry *whiteout; + struct name_snapshot name; + int err; + + inode_lock_nested(dir, I_MUTEX_PARENT); + + temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0)); + err = PTR_ERR(temp); + if (IS_ERR(temp)) + goto out_unlock; + + dest = ovl_lookup_temp(workdir); + err = PTR_ERR(dest); + if (IS_ERR(dest)) { + dput(temp); + goto out_unlock; + } + + /* Name is inline and stable - using snapshot as a copy helper */ + take_dentry_name_snapshot(&name, temp); + err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT); + if (err) { + if (err == -EINVAL) + err = 0; + goto cleanup_temp; + } + + whiteout = lookup_one_len(name.name.name, workdir, name.name.len); + err = PTR_ERR(whiteout); + if (IS_ERR(whiteout)) + goto cleanup_temp; + + err = ovl_is_whiteout(whiteout); + + /* Best effort cleanup of whiteout and temp file */ + if (err) + ovl_cleanup(dir, whiteout); + dput(whiteout); + +cleanup_temp: + ovl_cleanup(dir, temp); + release_dentry_name_snapshot(&name); + dput(temp); + dput(dest); + +out_unlock: + inode_unlock(dir); + + return err; +} + static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, struct path *workpath) { @@ -1116,6 +1176,15 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, else pr_warn("upper fs does not support tmpfile.\n"); + + /* Check if upper/work fs supports RENAME_WHITEOUT */ + err = ovl_check_rename_whiteout(ofs->workdir); + if (err < 0) + goto out; + + if (!err) + pr_warn("upper fs does not support RENAME_WHITEOUT.\n"); + /* * Check if upper/work fs supports trusted.overlay.* xattr */ -- cgit v1.2.3