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author | Miklos Szeredi <mszeredi@suse.cz> | 2014-12-13 02:59:44 +0300 |
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committer | Miklos Szeredi <mszeredi@suse.cz> | 2014-12-13 02:59:44 +0300 |
commit | 3d3c6b89399a1b5e8a59ffbb8cb2a7797a9ef154 (patch) | |
tree | 81ec06b0edc6cff0d809d06228e5b2604119b33f | |
parent | 9d7459d834c28f55c82f1737f638a6c90e0c0e0f (diff) | |
download | linux-3d3c6b89399a1b5e8a59ffbb8cb2a7797a9ef154.tar.xz |
ovl: multi-layer lookup
Look up dentry in all relevant layers.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
-rw-r--r-- | fs/overlayfs/super.c | 143 |
1 files changed, 94 insertions, 49 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index c245043aa1b9..f72b82fdc1e6 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -333,82 +333,127 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { struct ovl_entry *oe; - struct dentry *upperdir; - struct path lowerdir; - struct dentry *upperdentry = NULL; - struct dentry *lowerdentry = NULL; + struct ovl_entry *poe = dentry->d_parent->d_fsdata; + struct path *stack = NULL; + struct dentry *upperdir, *upperdentry = NULL; + unsigned int ctr = 0; struct inode *inode = NULL; + bool upperopaque = false; + struct dentry *this, *prev = NULL; + unsigned int i; int err; - err = -ENOMEM; - oe = ovl_alloc_entry(1); - if (!oe) - goto out; - - upperdir = ovl_dentry_upper(dentry->d_parent); - ovl_path_lower(dentry->d_parent, &lowerdir); - + upperdir = ovl_upperdentry_dereference(poe); if (upperdir) { - upperdentry = ovl_lookup_real(upperdir, &dentry->d_name); - err = PTR_ERR(upperdentry); - if (IS_ERR(upperdentry)) - goto out_put_dir; - - if (lowerdir.dentry && upperdentry) { - if (ovl_is_whiteout(upperdentry)) { - dput(upperdentry); - upperdentry = NULL; - oe->opaque = true; - } else if (ovl_is_opaquedir(upperdentry)) { - oe->opaque = true; + this = ovl_lookup_real(upperdir, &dentry->d_name); + err = PTR_ERR(this); + if (IS_ERR(this)) + goto out; + + /* + * If this is not the lowermost layer, check whiteout and opaque + * directory. + */ + if (poe->numlower && this) { + if (ovl_is_whiteout(this)) { + dput(this); + this = NULL; + upperopaque = true; + } else if (ovl_is_opaquedir(this)) { + upperopaque = true; } } + upperdentry = prev = this; } - if (lowerdir.dentry && !oe->opaque) { - lowerdentry = ovl_lookup_real(lowerdir.dentry, &dentry->d_name); - err = PTR_ERR(lowerdentry); - if (IS_ERR(lowerdentry)) - goto out_dput_upper; + + if (!upperopaque && poe->numlower) { + err = -ENOMEM; + stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); + if (!stack) + goto out_put_upper; } - if (lowerdentry && upperdentry && - (!S_ISDIR(upperdentry->d_inode->i_mode) || - !S_ISDIR(lowerdentry->d_inode->i_mode))) { - dput(lowerdentry); - lowerdentry = NULL; - oe->opaque = true; + for (i = 0; !upperopaque && i < poe->numlower; i++) { + bool opaque = false; + struct path lowerpath = poe->lowerstack[i]; + + opaque = false; + this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name); + err = PTR_ERR(this); + if (IS_ERR(this)) + goto out_put; + if (!this) + continue; + + /* + * If this is not the lowermost layer, check whiteout and opaque + * directory. + */ + if (i < poe->numlower - 1) { + if (ovl_is_whiteout(this)) { + dput(this); + break; + } else if (ovl_is_opaquedir(this)) { + opaque = true; + } + } + /* + * If this is a non-directory then stop here. + * + * FIXME: check for opaqueness maybe better done in remove code. + */ + if (!S_ISDIR(this->d_inode->i_mode)) { + opaque = true; + } else if (prev && (!S_ISDIR(prev->d_inode->i_mode) || + !S_ISDIR(this->d_inode->i_mode))) { + if (prev == upperdentry) + upperopaque = true; + dput(this); + break; + } + stack[ctr].dentry = this; + stack[ctr].mnt = lowerpath.mnt; + ctr++; + prev = this; + if (opaque) + break; } - if (lowerdentry || upperdentry) { + oe = ovl_alloc_entry(ctr); + err = -ENOMEM; + if (!oe) + goto out_put; + + if (upperdentry || ctr) { struct dentry *realdentry; - realdentry = upperdentry ? upperdentry : lowerdentry; + realdentry = upperdentry ? upperdentry : stack[0].dentry; + err = -ENOMEM; inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode, oe); if (!inode) - goto out_dput; + goto out_free_oe; ovl_copyattr(realdentry->d_inode, inode); } + oe->opaque = upperopaque; oe->__upperdentry = upperdentry; - if (lowerdentry) { - oe->lowerstack[0].dentry = lowerdentry; - oe->lowerstack[0].mnt = lowerdir.mnt; - } else { - oe->numlower = 0; - } + memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); + kfree(stack); dentry->d_fsdata = oe; d_add(dentry, inode); return NULL; -out_dput: - dput(lowerdentry); -out_dput_upper: - dput(upperdentry); -out_put_dir: +out_free_oe: kfree(oe); +out_put: + for (i = 0; i < ctr; i++) + dput(stack[i].dentry); + kfree(stack); +out_put_upper: + dput(upperdentry); out: return ERR_PTR(err); } |