On Mon, Oct 30, 2017 at 10:27:25PM +0200, Amir Goldstein wrote:
> From: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
>
> For stat(2) on lowerdir non-dir entries in non-samefs case, this commit
> provides unique values for st_dev. The unique values are obtained by
> allocating anonymous bdevs for each of the lowerdirs in the overlayfs
> instance.
Hi Amir, Chandan,
In the commit message, can we also mention what's the current behavior
and why this new behavior beneficial/desirable.
Vivek
>
> Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
> [amir: rename to struct ovl_layer lower_layers and struct ovl_path]
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/inode.c | 18 +++++++++++
> fs/overlayfs/namei.c | 52 ++++++++++++++++++-------------
> fs/overlayfs/overlayfs.h | 4 +--
> fs/overlayfs/ovl_entry.h | 14 +++++++--
> fs/overlayfs/readdir.c | 4 +--
> fs/overlayfs/super.c | 80 ++++++++++++++++++++++++++++++------------------
> fs/overlayfs/util.c | 7 ++++-
> 7 files changed, 121 insertions(+), 58 deletions(-)
>
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 50e233ccca53..ec5c3ce91868 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -8,6 +8,7 @@
> */
>
> #include <linux/fs.h>
> +#include <linux/mount.h>
> #include <linux/slab.h>
> #include <linux/cred.h>
> #include <linux/xattr.h>
> @@ -15,6 +16,21 @@
> #include <linux/ratelimit.h>
> #include "overlayfs.h"
>
> +
> +static dev_t ovl_get_pseudo_dev(struct dentry *dentry, dev_t dev)
> +{
> + struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
> + struct ovl_entry *oe = dentry->d_fsdata;
> +
> + if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb->s_dev == dev)
> + return dev;
> +
> + if (oe->numlower)
> + return oe->lowerstack[0].layer->pseudo_dev;
> +
> + return dev;
> +}
> +
> int ovl_setattr(struct dentry *dentry, struct iattr *attr)
> {
> int err;
> @@ -121,6 +137,8 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
> */
> stat->dev = dentry->d_sb->s_dev;
> stat->ino = dentry->d_inode->i_ino;
> + } else {
> + stat->dev = ovl_get_pseudo_dev(dentry, stat->dev);
> }
>
> /*
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index de2dac98e147..78e965527167 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 @@ int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
> * 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)
> @@ -570,11 +569,24 @@ int ovl_path_next(int idx, struct dentry *dentry, struct path *path, int *idxp)
> }
> BUG_ON(idx > oe->numlower);
> *idxp = idx;
> - *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)
> {
> @@ -583,7 +595,7 @@ 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;
> @@ -648,17 +660,17 @@ 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;
>
> @@ -666,7 +678,7 @@ 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)
> @@ -676,10 +688,8 @@ 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;
> }
> }
> @@ -702,7 +712,7 @@ 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 73ef1e850635..335e9a052995 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -248,7 +248,7 @@ 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, int *idxp);
> @@ -265,7 +265,7 @@ 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 25d9b5adcd42..93eb6a044dd2 100644
> --- a/fs/overlayfs/ovl_entry.h
> +++ b/fs/overlayfs/ovl_entry.h
> @@ -17,11 +17,21 @@ struct ovl_config {
> bool index;
> };
>
> +struct ovl_layer {
> + struct vfsmount *mnt;
> + dev_t pseudo_dev;
> +};
> +
> +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 +62,7 @@ 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 bcc123c7706c..0ab657f2c1c8 100644
> --- a/fs/overlayfs/readdir.c
> +++ b/fs/overlayfs/readdir.c
> @@ -1020,7 +1020,7 @@ 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;
> @@ -1055,7 +1055,7 @@ 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 8702803ba328..323dfd7a0236 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -219,9 +219,11 @@ static void ovl_put_super(struct super_block *sb)
> if (ufs->upper_mnt && ufs->upperdir_locked)
> 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);
> + for (i = 0; i < ufs->numlower; i++) {
> + mntput(ufs->lower_layers[i].mnt);
> + free_anon_bdev(ufs->lower_layers[i].pseudo_dev);
> + }
> + kfree(ufs->lower_layers);
>
> kfree(ufs->config.lowerdir);
> kfree(ufs->config.upperdir);
> @@ -1026,24 +1028,35 @@ 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;
> + dev_t dev;
> +
> + err = get_anon_bdev(&dev);
> + if (err) {
> + pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
> + goto out_put_lower_layers;
> + }
>
> + 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;
> + free_anon_bdev(dev);
> + 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->lower_layers[ufs->numlower].pseudo_dev = dev;
> ufs->numlower++;
>
> /* Check if all lower layers are on same sb */
> @@ -1059,13 +1072,25 @@ 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 +1106,8 @@ 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 +1132,6 @@ 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 +1140,12 @@ 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 +1154,6 @@ 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;
>
> @@ -1147,16 +1164,19 @@ 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:
> - for (i = 0; i < ufs->numlower; i++)
> - mntput(ufs->lower_mnt[i]);
> - kfree(ufs->lower_mnt);
> +out_free_oe:
> + kfree(oe);
> +out_put_lower_layers:
> + for (i = 0; i < ufs->numlower; i++) {
> + if (ufs->lower_layers[i].mnt)
> + free_anon_bdev(ufs->lower_layers[i].pseudo_dev);
> + 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 9158d17bb320..d6bb1c9f5e7a 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
>
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