On Tue, Oct 31, 2017 at 3:53 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> 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.
>
Pushed the requested changes to branch:
https://github.com/amir73il/linux/commits/ovl-nonsamefs-v6
Currently same tip as overlayfs-devel.
Amir.
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