On Tue, Oct 31, 2017 at 3:43 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> On Mon, Oct 30, 2017 at 9:27 PM, Amir Goldstein <amir73il@xxxxxxxxx> 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.
>>
>> 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;
>
> This doesn't feel right. Okay, we may want to check against upper
> device number for sanity and WARN if doesn't match, although we can
> have all sorts of weirdness with btrfs, for example. So the logic
> should be:
>
> if type is upper then use the dev returned by stat
> else return the pseudo 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);
>> }
>>
>> /*
>
> The above can be a separate patch. I.e. split this into:
>
> 1) add ovl_layer infrastructure
> 2) use that infrastructure in getattr
>
> 1) doesn't change functionality while 2) does.
>
>> 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);
>
> I'm not even attempting to review the ovl_fill_super() changes. We
> need to do something about that function (it's my fault for letting it
> grow this big and convoluted). Do you want me to have a go at
> cleaning it up? Or do you feel an urging desire to do so?
>
Well, I am up to my neck with the NFS export patches and besides
I probably won't get the cleanup done the way you would ;-)
so I prefer you have a go at it and I will rebase the patches on top
of your cleanup.
Thanks,
Amir.
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