From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amir Goldstein Subject: [PATCH v2 15/17] ovl: lookup indexed ancestor of lower dir Date: Thu, 4 Jan 2018 19:20:47 +0200 Message-ID: <1515086449-26563-16-git-send-email-amir73il@gmail.com> References: <1515086449-26563-1-git-send-email-amir73il@gmail.com> Return-path: In-Reply-To: <1515086449-26563-1-git-send-email-amir73il@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org To: Miklos Szeredi Cc: Jeff Layton , "J . Bruce Fields" , linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org List-Id: linux-unionfs@vger.kernel.org ovl_lookup_real(is_upper=false) walks back lower parents to find the topmost indexed parent. If an indexed ancestor is found before reaching lower layer root, ovl_lookup_real(is_upper=true) is called recursively to walk back from indexed upper to the topmost connected/hashed upper parent (or up to root). ovl_lookup_real(is_upper=true) then walks forward to connect the topmost upper overlay dir dentry and ovl_lookup_real(is_upper=false) continues to walk forward to connect the decoded lower overlay dir dentry. Signed-off-by: Amir Goldstein --- fs/overlayfs/export.c | 39 ++++++++++++++++++++++++++++++++++++++- fs/overlayfs/namei.c | 20 ++++++++++++++------ fs/overlayfs/overlayfs.h | 2 ++ 3 files changed, 54 insertions(+), 7 deletions(-) diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c index 01c4e3f733c1..147d9061cc40 100644 --- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -257,15 +257,24 @@ static struct dentry *ovl_lookup_real_one(struct dentry *parent, return ERR_PTR(err); } +static struct dentry *ovl_lookup_real(struct super_block *sb, + struct dentry *real, bool is_upper); + /* * Lookup an indexed or hashed overlay dentry by real inode. */ static struct dentry *ovl_lookup_real_inode(struct super_block *sb, struct dentry *real, bool is_upper) { + struct ovl_fs *ofs = sb->s_fs_info; + struct dentry *index = NULL; struct dentry *this = NULL; struct inode *inode; + /* + * Decoding upper dir from index is expensive, so first try to lookup + * overlay dentry in inode/dcache. + */ inode = ovl_lookup_inode(sb, real, is_upper); if (IS_ERR(inode)) return ERR_CAST(inode); @@ -274,7 +283,35 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb, iput(inode); } - /* TODO: use index when looking up by origin inode */ + /* + * For decoded lower dir file handle, lookup index by origin to check + * if lower dir was copied up and and/or removed. + */ + if (!this && !is_upper && !WARN_ON(!d_is_dir(real))) { + index = ovl_lookup_index(ofs, NULL, real, false); + if (IS_ERR(index)) + return index; + } + + /* Get connected upper overlay dir from index */ + if (index) { + struct dentry *upper = ovl_index_upper(ofs, index); + + dput(index); + if (IS_ERR_OR_NULL(upper)) + return upper; + + /* + * ovl_lookup_real(is_upper=false) may call recursively once to + * ovl_lookup_real(is_upper=true). The first level call walks + * back lower parents to the topmost indexed parent. The second + * recursive call walks back from indexed upper to the topmost + * connected/hashed upper parent (or up to root). + */ + this = ovl_lookup_real(sb, upper, true); + dput(upper); + } + if (!this) return NULL; diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 13869108dc32..f728942a5a1f 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -665,11 +665,9 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh) return ERR_PTR(err); } -static struct dentry *ovl_lookup_index(struct dentry *dentry, - struct dentry *upper, - struct dentry *origin) +struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper, + struct dentry *origin, bool verify) { - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; struct dentry *index; struct inode *inode; struct qstr name; @@ -697,6 +695,16 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry, inode = d_inode(index); if (d_is_negative(index)) { goto out_dput; + } else if (ovl_is_whiteout(index) && !verify) { + /* + * When index lookup is called with !verify for decoding an + * overlay file handle, a whiteout index implies that decode + * should treat file handle as stale and no need to print a + * warning about it. + */ + dput(index); + index = ERR_PTR(-ESTALE); + goto out; } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) || ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) { /* @@ -710,7 +718,7 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry, index, d_inode(index)->i_mode & S_IFMT, d_inode(origin)->i_mode & S_IFMT); goto fail; - } else if (is_dir) { + } else if (is_dir && verify) { if (!upper) { pr_warn_ratelimited("overlayfs: suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n", origin, index); @@ -948,7 +956,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, if (origin && ovl_indexdir(dentry->d_sb) && (!d.is_dir || ovl_verify(dentry->d_sb))) { - index = ovl_lookup_index(dentry, upperdentry, origin); + index = ovl_lookup_index(ofs, upperdentry, origin, true); if (IS_ERR(index)) { err = PTR_ERR(index); index = NULL; diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index d06299b27ec3..661f33bd9793 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -269,6 +269,8 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index); int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index); int ovl_get_index_name(struct dentry *origin, struct qstr *name); struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh); +struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper, + struct dentry *origin, bool verify); int ovl_path_next(int idx, struct dentry *dentry, struct path *path); struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags); -- 2.7.4