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authorAmir Goldstein <amir73il@gmail.com>2018-01-17 07:40:27 -0500
committerMiklos Szeredi <mszeredi@redhat.com>2018-01-24 05:26:05 -0500
commit061701540349c30d72e48a201449a840c77ad509 (patch)
tree46d3e9191ba287cd420af0a41bd5aba86bb50a89
parent4b91c30a5a19332e8dd10b601d05b72caf657730 (diff)
ovl: lookup indexed ancestor of lower dir
ovl_lookup_real() in lower layer 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 called recursively with upper layer to walk back from indexed upper to the topmost connected/hashed upper parent (or up to root). ovl_lookup_real() in upper layer then walks forward to connect the topmost upper overlay dir dentry and ovl_lookup_real() in lower layer continues to walk forward to connect the decoded lower overlay dir dentry. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/overlayfs/export.c41
-rw-r--r--fs/overlayfs/namei.c20
-rw-r--r--fs/overlayfs/overlayfs.h2
3 files changed, 56 insertions, 7 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 092e6e8c9258..b65ea49de457 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -294,6 +294,10 @@ fail:
294 goto out; 294 goto out;
295} 295}
296 296
297static struct dentry *ovl_lookup_real(struct super_block *sb,
298 struct dentry *real,
299 struct ovl_layer *layer);
300
297/* 301/*
298 * Lookup an indexed or hashed overlay dentry by real inode. 302 * Lookup an indexed or hashed overlay dentry by real inode.
299 */ 303 */
@@ -301,9 +305,16 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
301 struct dentry *real, 305 struct dentry *real,
302 struct ovl_layer *layer) 306 struct ovl_layer *layer)
303{ 307{
308 struct ovl_fs *ofs = sb->s_fs_info;
309 struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
310 struct dentry *index = NULL;
304 struct dentry *this = NULL; 311 struct dentry *this = NULL;
305 struct inode *inode; 312 struct inode *inode;
306 313
314 /*
315 * Decoding upper dir from index is expensive, so first try to lookup
316 * overlay dentry in inode/dcache.
317 */
307 inode = ovl_lookup_inode(sb, real, !layer->idx); 318 inode = ovl_lookup_inode(sb, real, !layer->idx);
308 if (IS_ERR(inode)) 319 if (IS_ERR(inode))
309 return ERR_CAST(inode); 320 return ERR_CAST(inode);
@@ -312,7 +323,35 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
312 iput(inode); 323 iput(inode);
313 } 324 }
314 325
315 /* TODO: use index when looking up by origin inode */ 326 /*
327 * For decoded lower dir file handle, lookup index by origin to check
328 * if lower dir was copied up and and/or removed.
329 */
330 if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {
331 index = ovl_lookup_index(ofs, NULL, real, false);
332 if (IS_ERR(index))
333 return index;
334 }
335
336 /* Get connected upper overlay dir from index */
337 if (index) {
338 struct dentry *upper = ovl_index_upper(ofs, index);
339
340 dput(index);
341 if (IS_ERR_OR_NULL(upper))
342 return upper;
343
344 /*
345 * ovl_lookup_real() in lower layer may call recursively once to
346 * ovl_lookup_real() in upper layer. The first level call walks
347 * back lower parents to the topmost indexed parent. The second
348 * recursive call walks back from indexed upper to the topmost
349 * connected/hashed upper parent (or up to root).
350 */
351 this = ovl_lookup_real(sb, upper, &upper_layer);
352 dput(upper);
353 }
354
316 if (!this) 355 if (!this)
317 return NULL; 356 return NULL;
318 357
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 6199bf7a77c7..c5449efd96d5 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -661,11 +661,9 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
661 return ERR_PTR(err); 661 return ERR_PTR(err);
662} 662}
663 663
664static struct dentry *ovl_lookup_index(struct dentry *dentry, 664struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
665 struct dentry *upper, 665 struct dentry *origin, bool verify)
666 struct dentry *origin)
667{ 666{
668 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
669 struct dentry *index; 667 struct dentry *index;
670 struct inode *inode; 668 struct inode *inode;
671 struct qstr name; 669 struct qstr name;
@@ -693,6 +691,16 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
693 inode = d_inode(index); 691 inode = d_inode(index);
694 if (d_is_negative(index)) { 692 if (d_is_negative(index)) {
695 goto out_dput; 693 goto out_dput;
694 } else if (ovl_is_whiteout(index) && !verify) {
695 /*
696 * When index lookup is called with !verify for decoding an
697 * overlay file handle, a whiteout index implies that decode
698 * should treat file handle as stale and no need to print a
699 * warning about it.
700 */
701 dput(index);
702 index = ERR_PTR(-ESTALE);
703 goto out;
696 } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) || 704 } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
697 ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) { 705 ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
698 /* 706 /*
@@ -706,7 +714,7 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
706 index, d_inode(index)->i_mode & S_IFMT, 714 index, d_inode(index)->i_mode & S_IFMT,
707 d_inode(origin)->i_mode & S_IFMT); 715 d_inode(origin)->i_mode & S_IFMT);
708 goto fail; 716 goto fail;
709 } else if (is_dir) { 717 } else if (is_dir && verify) {
710 if (!upper) { 718 if (!upper) {
711 pr_warn_ratelimited("overlayfs: suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n", 719 pr_warn_ratelimited("overlayfs: suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
712 origin, index); 720 origin, index);
@@ -943,7 +951,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
943 951
944 if (origin && ovl_indexdir(dentry->d_sb) && 952 if (origin && ovl_indexdir(dentry->d_sb) &&
945 (!d.is_dir || ovl_index_all(dentry->d_sb))) { 953 (!d.is_dir || ovl_index_all(dentry->d_sb))) {
946 index = ovl_lookup_index(dentry, upperdentry, origin); 954 index = ovl_lookup_index(ofs, upperdentry, origin, true);
947 if (IS_ERR(index)) { 955 if (IS_ERR(index)) {
948 err = PTR_ERR(index); 956 err = PTR_ERR(index);
949 index = NULL; 957 index = NULL;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index bf17bf97c50f..0df25a9c94bd 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -274,6 +274,8 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
274int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index); 274int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
275int ovl_get_index_name(struct dentry *origin, struct qstr *name); 275int ovl_get_index_name(struct dentry *origin, struct qstr *name);
276struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh); 276struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
277struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
278 struct dentry *origin, bool verify);
277int ovl_path_next(int idx, struct dentry *dentry, struct path *path); 279int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
278struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 280struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
279 unsigned int flags); 281 unsigned int flags);