From b93436320c1e9089a055941523571cd7c037f7cb Mon Sep 17 00:00:00 2001 From: Chandan Rajendra Date: Mon, 24 Jul 2017 01:57:54 -0500 Subject: [PATCH] ovl: re-structure overlay lower layers in-memory Define new structures to represent overlay instance lower layers and overlay merge dir lower layers to make room for storing more per layer information in-memory. Instead of keeping the fs instance lower layers in an array of struct vfsmount, keep them in an array of new struct ovl_layer, that has a pointer to struct vfsmount. Instead of keeping the dentry lower layers in an array of struct path, keep them in an array of new struct ovl_path, that has a pointer to struct dentry and to struct ovl_layer. Add a small helper to find the fs layer id that correspopnds to a lower struct ovl_path and use it in ovl_lookup(). [amir: split re-structure from anonymous bdev patch] Signed-off-by: Chandan Rajendra Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/namei.c | 52 ++++++++++++++++++++++++---------------- fs/overlayfs/overlayfs.h | 4 ++-- fs/overlayfs/ovl_entry.h | 13 ++++++++-- fs/overlayfs/readdir.c | 4 ++-- fs/overlayfs/super.c | 62 ++++++++++++++++++++++++++---------------------- fs/overlayfs/util.c | 7 +++++- 6 files changed, 86 insertions(+), 56 deletions(-) diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 505a4b8..6cc3ece3 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -285,16 +285,15 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, static int ovl_check_origin(struct dentry *upperdentry, - struct path *lowerstack, unsigned int numlower, - struct path **stackp, unsigned int *ctrp) + struct ovl_path *lower, unsigned int numlower, + struct ovl_path **stackp, unsigned int *ctrp) { struct vfsmount *mnt; struct dentry *origin = NULL; int i; - for (i = 0; i < numlower; i++) { - mnt = lowerstack[i].mnt; + mnt = lower[i].layer->mnt; origin = ovl_get_origin(upperdentry, mnt); if (IS_ERR(origin)) return PTR_ERR(origin); @@ -308,12 +307,12 @@ static int ovl_check_origin(struct dentry *upperdentry, BUG_ON(*ctrp); if (!*stackp) - *stackp = kmalloc(sizeof(struct path), GFP_KERNEL); + *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL); if (!*stackp) { dput(origin); return -ENOMEM; } - **stackp = (struct path) { .dentry = origin, .mnt = mnt }; + **stackp = (struct ovl_path){.dentry = origin, .layer = lower[i].layer}; *ctrp = 1; return 0; @@ -383,13 +382,13 @@ fail: * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path. * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error. */ -int ovl_verify_index(struct dentry *index, struct path *lowerstack, +int ovl_verify_index(struct dentry *index, struct ovl_path *lower, unsigned int numlower) { struct ovl_fh *fh = NULL; size_t len; - struct path origin = { }; - struct path *stack = &origin; + struct ovl_path origin = { }; + struct ovl_path *stack = &origin; unsigned int ctr = 0; int err; @@ -428,7 +427,7 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack, if (err) goto fail; - err = ovl_check_origin(index, lowerstack, numlower, &stack, &ctr); + err = ovl_check_origin(index, lower, numlower, &stack, &ctr); if (!err && !ctr) err = -ESTALE; if (err) @@ -567,11 +566,24 @@ int ovl_path_next(int idx, struct dentry *dentry, struct path *path) idx++; } BUG_ON(idx > oe->numlower); - *path = oe->lowerstack[idx - 1]; + path->dentry = oe->lowerstack[idx - 1].dentry; + path->mnt = oe->lowerstack[idx - 1].layer->mnt; return (idx < oe->numlower) ? idx + 1 : -1; } +static int ovl_find_layer(struct ovl_fs *ofs, struct ovl_path *path) +{ + int i; + + for (i = 0; i < ofs->numlower; i++) { + if (ofs->lower_layers[i].mnt == path->layer->mnt) + break; + } + + return i; +} + struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { @@ -580,7 +592,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, struct ovl_fs *ofs = dentry->d_sb->s_fs_info; struct ovl_entry *poe = dentry->d_parent->d_fsdata; struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata; - struct path *stack = NULL; + struct ovl_path *stack = NULL; struct dentry *upperdir, *upperdentry = NULL; struct dentry *index = NULL; unsigned int ctr = 0; @@ -645,17 +657,17 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, if (!d.stop && poe->numlower) { err = -ENOMEM; - stack = kcalloc(ofs->numlower, sizeof(struct path), + stack = kcalloc(ofs->numlower, sizeof(struct ovl_path), GFP_KERNEL); if (!stack) goto out_put_upper; } for (i = 0; !d.stop && i < poe->numlower; i++) { - struct path lowerpath = poe->lowerstack[i]; + struct ovl_path lower = poe->lowerstack[i]; d.last = i == poe->numlower - 1; - err = ovl_lookup_layer(lowerpath.dentry, &d, &this); + err = ovl_lookup_layer(lower.dentry, &d, &this); if (err) goto out_put; @@ -663,7 +675,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, continue; stack[ctr].dentry = this; - stack[ctr].mnt = lowerpath.mnt; + stack[ctr].layer = lower.layer; ctr++; if (d.stop) @@ -673,10 +685,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, poe = roe; /* Find the current layer on the root dentry */ - for (i = 0; i < poe->numlower; i++) - if (poe->lowerstack[i].mnt == lowerpath.mnt) - break; - if (WARN_ON(i == poe->numlower)) + i = ovl_find_layer(ofs, &lower); + if (WARN_ON(i == ofs->numlower)) break; } } @@ -699,7 +709,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, goto out_put; oe->opaque = upperopaque; - memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); + memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr); dentry->d_fsdata = oe; if (upperdentry) diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 1cf3bdd..cefe5a9 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -251,7 +251,7 @@ static inline bool ovl_is_impuredir(struct dentry *dentry) /* namei.c */ int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt, struct dentry *origin, bool is_upper, bool set); -int ovl_verify_index(struct dentry *index, struct path *lowerstack, +int ovl_verify_index(struct dentry *index, struct ovl_path *lower, unsigned int numlower); int ovl_get_index_name(struct dentry *origin, struct qstr *name); int ovl_path_next(int idx, struct dentry *dentry, struct path *path); @@ -268,7 +268,7 @@ int ovl_check_d_type_supported(struct path *realpath); void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt, struct dentry *dentry, int level); int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt, - struct path *lowerstack, unsigned int numlower); + struct ovl_path *lower, unsigned int numlower); /* inode.c */ int ovl_set_nlink_upper(struct dentry *dentry); diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 25d9b5a..1e28329 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -17,11 +17,20 @@ struct ovl_config { bool index; }; +struct ovl_layer { + struct vfsmount *mnt; +}; + +struct ovl_path { + struct ovl_layer *layer; + struct dentry *dentry; +}; + /* private information held for overlayfs's superblock */ struct ovl_fs { struct vfsmount *upper_mnt; unsigned numlower; - struct vfsmount **lower_mnt; + struct ovl_layer *lower_layers; /* workbasedir is the path at workdir= mount option */ struct dentry *workbasedir; /* workdir is the 'work' directory under workbasedir */ @@ -52,7 +61,7 @@ struct ovl_entry { struct rcu_head rcu; }; unsigned numlower; - struct path lowerstack[]; + struct ovl_path lowerstack[]; }; struct ovl_entry *ovl_alloc_entry(unsigned int numlower); diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index a5ad5b3..914e77e 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -1014,7 +1014,7 @@ void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt, } int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt, - struct path *lowerstack, unsigned int numlower) + struct ovl_path *lower, unsigned int numlower) { int err; struct dentry *index = NULL; @@ -1049,7 +1049,7 @@ int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt, index = NULL; break; } - err = ovl_verify_index(index, lowerstack, numlower); + err = ovl_verify_index(index, lower, numlower); /* Cleanup stale and orphan index entries */ if (err && (err == -ESTALE || err == -ENOENT)) err = ovl_cleanup(dir, index); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index e3d49e9..a10fff4 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -220,8 +220,8 @@ static void ovl_put_super(struct super_block *sb) ovl_inuse_unlock(ufs->upper_mnt->mnt_root); mntput(ufs->upper_mnt); for (i = 0; i < ufs->numlower; i++) - mntput(ufs->lower_mnt[i]); - kfree(ufs->lower_mnt); + mntput(ufs->lower_layers[i].mnt); + kfree(ufs->lower_layers); kfree(ufs->config.lowerdir); kfree(ufs->config.upperdir); @@ -1026,24 +1026,26 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) } err = -ENOMEM; - ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL); - if (ufs->lower_mnt == NULL) + ufs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer), + GFP_KERNEL); + if (ufs->lower_layers == NULL) goto out_put_workdir; for (i = 0; i < numlower; i++) { - struct vfsmount *mnt = clone_private_mount(&stack[i]); + struct vfsmount *mnt; + mnt = clone_private_mount(&stack[i]); err = PTR_ERR(mnt); if (IS_ERR(mnt)) { pr_err("overlayfs: failed to clone lowerpath\n"); - goto out_put_lower_mnt; + goto out_put_lower_layers; } /* - * Make lower_mnt R/O. That way fchmod/fchown on lower file + * Make lower layers R/O. That way fchmod/fchown on lower file * will fail instead of modifying lower fs. */ mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; - ufs->lower_mnt[ufs->numlower] = mnt; + ufs->lower_layers[ufs->numlower].mnt = mnt; ufs->numlower++; /* Check if all lower layers are on same sb */ @@ -1059,13 +1061,25 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) else if (ufs->upper_mnt->mnt_sb != ufs->same_sb) ufs->same_sb = NULL; + err = -ENOMEM; + oe = ovl_alloc_entry(numlower); + if (!oe) + goto out_put_lower_layers; + + for (i = 0; i < numlower; i++) { + oe->lowerstack[i].dentry = stack[i].dentry; + oe->lowerstack[i].layer = &(ufs->lower_layers[i]); + } + if (!(ovl_force_readonly(ufs)) && ufs->config.index) { /* Verify lower root is upper root origin */ - err = ovl_verify_origin(upperpath.dentry, ufs->lower_mnt[0], - stack[0].dentry, false, true); + err = ovl_verify_origin(upperpath.dentry, + oe->lowerstack[0].layer->mnt, + oe->lowerstack[0].dentry, + false, true); if (err) { pr_err("overlayfs: failed to verify upper root origin\n"); - goto out_put_lower_mnt; + goto out_free_oe; } ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry, @@ -1081,7 +1095,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (!err) err = ovl_indexdir_cleanup(ufs->indexdir, ufs->upper_mnt, - stack, numlower); + oe->lowerstack, + numlower); } if (err || !ufs->indexdir) pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); @@ -1106,11 +1121,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) /* Never override disk quota limits or use reserved space */ cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); - err = -ENOMEM; - oe = ovl_alloc_entry(numlower); - if (!oe) - goto out_put_cred; - sb->s_magic = OVERLAYFS_SUPER_MAGIC; sb->s_op = &ovl_super_operations; sb->s_xattr = ovl_xattr_handlers; @@ -1119,11 +1129,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); if (!root_dentry) - goto out_free_oe; + goto out_put_cred; mntput(upperpath.mnt); for (i = 0; i < numlower; i++) mntput(stack[i].mnt); + kfree(stack); mntput(workpath.mnt); kfree(lowertmp); @@ -1132,11 +1143,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (ovl_is_impuredir(upperpath.dentry)) ovl_set_flag(OVL_IMPURE, d_inode(root_dentry)); } - for (i = 0; i < numlower; i++) { - oe->lowerstack[i].dentry = stack[i].dentry; - oe->lowerstack[i].mnt = ufs->lower_mnt[i]; - } - kfree(stack); root_dentry->d_fsdata = oe; @@ -1149,16 +1155,16 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) return 0; -out_free_oe: - kfree(oe); out_put_cred: put_cred(ufs->creator_cred); out_put_indexdir: dput(ufs->indexdir); -out_put_lower_mnt: +out_free_oe: + kfree(oe); +out_put_lower_layers: for (i = 0; i < ufs->numlower; i++) - mntput(ufs->lower_mnt[i]); - kfree(ufs->lower_mnt); + mntput(ufs->lower_layers[i].mnt); + kfree(ufs->lower_layers); out_put_workdir: dput(ufs->workdir); mntput(ufs->upper_mnt); diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 9158d17..d6bb1c9 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -124,7 +124,12 @@ void ovl_path_lower(struct dentry *dentry, struct path *path) { struct ovl_entry *oe = dentry->d_fsdata; - *path = oe->numlower ? oe->lowerstack[0] : (struct path) { }; + if (oe->numlower) { + path->mnt = oe->lowerstack[0].layer->mnt; + path->dentry = oe->lowerstack[0].dentry; + } else { + *path = (struct path) { }; + } } enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) -- 2.7.4