[RH7] ipc: add export_operations to mqueue sb

Submitted by Andrey Zhadchenko on Sept. 8, 2020, 2:33 p.m.

Details

Message ID 1599575591-630239-1-git-send-email-andrey.zhadchenko@virtuozzo.com
State New
Series "ipc: add export_operations to mqueue sb"
Headers show

Commit Message

Andrey Zhadchenko Sept. 8, 2020, 2:33 p.m.
criu uses fhandle from fdinfo to dump inotify objects, but mqueue has no
export_operations in super block. However, they are needed if we want to
operate with files using fhandles.
Add hash table as a storage for exported inodes.

https://jira.sw.ru/browse/PSBM-103727
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
---
 ipc/mqueue.c | 150 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)

Patch hide | download patch | download mbox

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 458e655..48ec6f8 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -35,6 +35,8 @@ 
 #include <linux/ipc_namespace.h>
 #include <linux/user_namespace.h>
 #include <linux/slab.h>
+#include <linux/exportfs.h>
+#include <linux/random.h>
 
 #include <net/sock.h>
 #include "util.h"
@@ -86,6 +88,7 @@  struct mqueue_inode_info {
 };
 
 static const struct inode_operations mqueue_dir_inode_operations;
+static const struct export_operations mqueue_export_ops;
 static const struct file_operations mqueue_file_operations;
 static const struct super_operations mqueue_super_ops;
 static void remove_notification(struct mqueue_inode_info *info);
@@ -117,6 +120,144 @@  static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 	return ns;
 }
 
+/*
+ * hashtable for inodes that have exported fhandles.
+ * When we export fhandle, we add it's inode into
+ * hashtable so we can find it fast
+ */
+
+#define MQUEUE_INODE_HASH_BITS 7
+static DEFINE_HASHTABLE(mqueue_inode_table, MQUEUE_INODE_HASH_BITS);
+static DEFINE_SPINLOCK(mqueue_inode_table_lock);
+
+struct mq_inode_hitem {
+	struct inode *inode;
+	struct hlist_node hlist;
+};
+
+static inline unsigned long mqueue_inode_get_hash(unsigned int i_ino)
+{
+	return hash_32(i_ino, MQUEUE_INODE_HASH_BITS);
+}
+
+static struct mq_inode_hitem *mqueue_find_item_no_lock(unsigned long fh[2])
+{
+	struct mq_inode_hitem *i;
+	struct hlist_head *head = mqueue_inode_table
+		+ mqueue_inode_get_hash(fh[1]);
+	struct mq_inode_hitem *found = NULL;
+
+	hlist_for_each_entry(i, head, hlist) {
+		if (i->inode->i_generation == fh[0] &&
+		    i->inode->i_ino == fh[1]) {
+			found = i;
+			break;
+		}
+	}
+
+	return found;
+}
+
+static struct inode *mqueue_find_inode(unsigned long fh[2], char take_ref)
+{
+	struct mq_inode_hitem *item;
+	struct inode *ret = NULL;
+
+	spin_lock(&mqueue_inode_table_lock);
+	item = mqueue_find_item_no_lock(fh);
+	if (item && take_ref && !igrab(item->inode))
+		item = NULL;
+	spin_unlock(&mqueue_inode_table_lock);
+
+	if (item)
+		ret = item->inode;
+
+	return ret;
+}
+
+static int mqueue_hash_add(struct inode *inode)
+{
+	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
+
+	if (!mqueue_find_inode(fh, 0)) {
+		struct mq_inode_hitem *item;
+		struct mq_inode_hitem *existing_item = 0;
+		struct hlist_head *head = mqueue_inode_table
+			+ mqueue_inode_get_hash(inode->i_ino);
+
+		item = kmalloc(sizeof(struct mq_inode_hitem), GFP_KERNEL);
+		if (!item)
+			return -ENOMEM;
+		item->inode = inode;
+
+		spin_lock(&mqueue_inode_table_lock);
+		existing_item = mqueue_find_item_no_lock(fh);
+		if (!existing_item)
+			hlist_add_head(&item->hlist, head);
+		spin_unlock(&mqueue_inode_table_lock);
+
+		if (existing_item)
+			kfree(item);
+	}
+
+	return 0;
+}
+
+static void mqueue_hash_del(struct inode *inode)
+{
+	struct mq_inode_hitem *item;
+	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
+
+	spin_lock(&mqueue_inode_table_lock);
+	item = mqueue_find_item_no_lock(fh);
+	if (item)
+		hlist_del(&item->hlist);
+	spin_unlock(&mqueue_inode_table_lock);
+
+	kfree(item);
+	return;
+}
+
+static struct dentry *mqueue_fh_to_dentry(struct super_block *sb,
+		struct fid *fid, int fh_len, int fh_type)
+{
+	struct inode *inode;
+	struct dentry *dentry = ERR_PTR(-ENOENT);
+	unsigned long fhandle[2] = {fid->raw[0], fid->raw[1]};
+
+	if (fh_len < 2)
+		return NULL;
+
+	inode = mqueue_find_inode(fhandle, 1);
+	if (inode) {
+		dentry = d_find_alias(inode);
+		iput(inode);
+	}
+	return dentry;
+}
+
+static int mqueue_encode_fh(struct inode *inode, __u32 *fh, int *len,
+				struct inode *parent)
+{
+	if (*len < 2) {
+		*len = 2;
+		return FILEID_INVALID;
+	}
+
+	/*
+	 * encode_fh is expected to return 255 (FILEID_INVALID)
+	 * in case of failure. We can't return ENOMEM, so
+	 * return FILEID_INVALID at least.
+	 */
+	if (mqueue_hash_add(inode))
+		return FILEID_INVALID;
+
+	fh[0] = inode->i_generation;
+	fh[1] = inode->i_ino;
+	*len = 2;
+	return 1;
+}
+
 /* Auxiliary functions to manipulate messages' list */
 static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
 {
@@ -226,6 +367,7 @@  static struct inode *mqueue_get_inode(struct super_block *sb,
 		goto err;
 
 	inode->i_ino = get_next_ino();
+	inode->i_generation = prandom_u32();
 	inode->i_mode = mode;
 	inode->i_uid = current_fsuid();
 	inode->i_gid = current_fsgid();
@@ -316,6 +458,7 @@  static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 	sb->s_magic = MQUEUE_MAGIC;
 	sb->s_op = &mqueue_super_ops;
+	sb->s_export_op = &mqueue_export_ops;
 
 	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 	if (IS_ERR(inode))
@@ -382,6 +525,8 @@  static void mqueue_evict_inode(struct inode *inode)
 	if (S_ISDIR(inode->i_mode))
 		return;
 
+	mqueue_hash_del(inode);
+
 	ipc_ns = get_ns_from_inode(inode);
 	info = MQUEUE_I(inode);
 	spin_lock(&info->lock);
@@ -1376,6 +1521,11 @@  static const struct inode_operations mqueue_dir_inode_operations = {
 	.unlink = mqueue_unlink,
 };
 
+static const struct export_operations mqueue_export_ops = {
+	.encode_fh      = mqueue_encode_fh,
+	.fh_to_dentry	= mqueue_fh_to_dentry,
+};
+
 static const struct file_operations mqueue_file_operations = {
 	.flush = mqueue_flush_file,
 	.poll = mqueue_poll_file,

Comments

Pavel Tikhomirov Sept. 9, 2020, 10:19 a.m.
Looks good.

Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>

But please also see two non-critical questions below.

On 9/8/20 5:33 PM, Andrey Zhadchenko wrote:
> criu uses fhandle from fdinfo to dump inotify objects, but mqueue has no
> export_operations in super block. However, they are needed if we want to
> operate with files using fhandles.
> Add hash table as a storage for exported inodes.
> 
> https://jira.sw.ru/browse/PSBM-103727
> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
> ---
>   ipc/mqueue.c | 150 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 150 insertions(+)
> 
> diff --git a/ipc/mqueue.c b/ipc/mqueue.c
> index 458e655..48ec6f8 100644
> --- a/ipc/mqueue.c
> +++ b/ipc/mqueue.c
> @@ -35,6 +35,8 @@
>   #include <linux/ipc_namespace.h>
>   #include <linux/user_namespace.h>
>   #include <linux/slab.h>
> +#include <linux/exportfs.h>
> +#include <linux/random.h>
>   
>   #include <net/sock.h>
>   #include "util.h"
> @@ -86,6 +88,7 @@ struct mqueue_inode_info {
>   };
>   
>   static const struct inode_operations mqueue_dir_inode_operations;
> +static const struct export_operations mqueue_export_ops;
>   static const struct file_operations mqueue_file_operations;
>   static const struct super_operations mqueue_super_ops;
>   static void remove_notification(struct mqueue_inode_info *info);
> @@ -117,6 +120,144 @@ static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
>   	return ns;
>   }
>   
> +/*
> + * hashtable for inodes that have exported fhandles.
> + * When we export fhandle, we add it's inode into
> + * hashtable so we can find it fast
> + */
> +
> +#define MQUEUE_INODE_HASH_BITS 7

Why you've chosen smaller hash size than for cgroups?
#define CGROUP_INODE_HASH_BITS 10

> +static DEFINE_HASHTABLE(mqueue_inode_table, MQUEUE_INODE_HASH_BITS);
> +static DEFINE_SPINLOCK(mqueue_inode_table_lock);
> +
> +struct mq_inode_hitem {
> +	struct inode *inode;
> +	struct hlist_node hlist;
> +};
> +
> +static inline unsigned long mqueue_inode_get_hash(unsigned int i_ino)
> +{
> +	return hash_32(i_ino, MQUEUE_INODE_HASH_BITS);
> +}
> +
> +static struct mq_inode_hitem *mqueue_find_item_no_lock(unsigned long fh[2])
> +{
> +	struct mq_inode_hitem *i;
> +	struct hlist_head *head = mqueue_inode_table
> +		+ mqueue_inode_get_hash(fh[1]);
> +	struct mq_inode_hitem *found = NULL;
> +
> +	hlist_for_each_entry(i, head, hlist) {
> +		if (i->inode->i_generation == fh[0] &&
> +		    i->inode->i_ino == fh[1]) {
> +			found = i;
> +			break;
> +		}
> +	}
> +
> +	return found;
> +}
> +
> +static struct inode *mqueue_find_inode(unsigned long fh[2], char take_ref)
> +{
> +	struct mq_inode_hitem *item;
> +	struct inode *ret = NULL;
> +
> +	spin_lock(&mqueue_inode_table_lock);
> +	item = mqueue_find_item_no_lock(fh);
> +	if (item && take_ref && !igrab(item->inode))
> +		item = NULL;
> +	spin_unlock(&mqueue_inode_table_lock);
> +
> +	if (item)
> +		ret = item->inode;
> +
> +	return ret;
> +}
> +
> +static int mqueue_hash_add(struct inode *inode)
> +{
> +	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
> +
> +	if (!mqueue_find_inode(fh, 0)) {
> +		struct mq_inode_hitem *item;
> +		struct mq_inode_hitem *existing_item = 0;
> +		struct hlist_head *head = mqueue_inode_table
> +			+ mqueue_inode_get_hash(inode->i_ino);
> +
> +		item = kmalloc(sizeof(struct mq_inode_hitem), GFP_KERNEL);
> +		if (!item)
> +			return -ENOMEM;
> +		item->inode = inode;
> +
> +		spin_lock(&mqueue_inode_table_lock);
> +		existing_item = mqueue_find_item_no_lock(fh);
> +		if (!existing_item)
> +			hlist_add_head(&item->hlist, head);
> +		spin_unlock(&mqueue_inode_table_lock);
> +
> +		if (existing_item)
> +			kfree(item);
> +	}
> +
> +	return 0;
> +}
> +
> +static void mqueue_hash_del(struct inode *inode)
> +{
> +	struct mq_inode_hitem *item;
> +	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
> +
> +	spin_lock(&mqueue_inode_table_lock);
> +	item = mqueue_find_item_no_lock(fh);
> +	if (item)
> +		hlist_del(&item->hlist);
> +	spin_unlock(&mqueue_inode_table_lock);
> +
> +	kfree(item);
> +	return;
> +}
> +
> +static struct dentry *mqueue_fh_to_dentry(struct super_block *sb,
> +		struct fid *fid, int fh_len, int fh_type)
> +{
> +	struct inode *inode;
> +	struct dentry *dentry = ERR_PTR(-ENOENT);
> +	unsigned long fhandle[2] = {fid->raw[0], fid->raw[1]};
> +
> +	if (fh_len < 2)
> +		return NULL;
> +
> +	inode = mqueue_find_inode(fhandle, 1);
> +	if (inode) {
> +		dentry = d_find_alias(inode);
> +		iput(inode);
> +	}
> +	return dentry;
> +}
> +
> +static int mqueue_encode_fh(struct inode *inode, __u32 *fh, int *len,
> +				struct inode *parent)
> +{
> +	if (*len < 2) {
> +		*len = 2;
> +		return FILEID_INVALID;
> +	}
> +
> +	/*
> +	 * encode_fh is expected to return 255 (FILEID_INVALID)
> +	 * in case of failure. We can't return ENOMEM, so
> +	 * return FILEID_INVALID at least.
> +	 */
> +	if (mqueue_hash_add(inode))
> +		return FILEID_INVALID;
> +
> +	fh[0] = inode->i_generation;
> +	fh[1] = inode->i_ino;
> +	*len = 2;
> +	return 1;
> +}
> +
>   /* Auxiliary functions to manipulate messages' list */
>   static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
>   {
> @@ -226,6 +367,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
>   		goto err;
>   
>   	inode->i_ino = get_next_ino();
> +	inode->i_generation = prandom_u32();
>   	inode->i_mode = mode;
>   	inode->i_uid = current_fsuid();
>   	inode->i_gid = current_fsgid();
> @@ -316,6 +458,7 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
>   	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
>   	sb->s_magic = MQUEUE_MAGIC;
>   	sb->s_op = &mqueue_super_ops;
> +	sb->s_export_op = &mqueue_export_ops;
>   
>   	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
>   	if (IS_ERR(inode))
> @@ -382,6 +525,8 @@ static void mqueue_evict_inode(struct inode *inode)
>   	if (S_ISDIR(inode->i_mode))
>   		return;
>   
> +	mqueue_hash_del(inode);
> +

Looks like for cgroups we should've also put cgroup_hash_del to 
->evict_inode helper, to be able to use igrab in cgroup_find_inode. 
Shouldn't we?

>   	ipc_ns = get_ns_from_inode(inode);
>   	info = MQUEUE_I(inode);
>   	spin_lock(&info->lock);
> @@ -1376,6 +1521,11 @@ static const struct inode_operations mqueue_dir_inode_operations = {
>   	.unlink = mqueue_unlink,
>   };
>   
> +static const struct export_operations mqueue_export_ops = {
> +	.encode_fh      = mqueue_encode_fh,
> +	.fh_to_dentry	= mqueue_fh_to_dentry,
> +};
> +
>   static const struct file_operations mqueue_file_operations = {
>   	.flush = mqueue_flush_file,
>   	.poll = mqueue_poll_file,
>
Konstantin Khorenko Sept. 24, 2020, 10:38 a.m.
On 09/09/2020 01:19 PM, Pavel Tikhomirov wrote:
> Looks good.
>
> Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
>
> But please also see two non-critical questions below.

Andrey, any answer on that?


> On 9/8/20 5:33 PM, Andrey Zhadchenko wrote:
>> criu uses fhandle from fdinfo to dump inotify objects, but mqueue has no
>> export_operations in super block. However, they are needed if we want to
>> operate with files using fhandles.
>> Add hash table as a storage for exported inodes.
>>
>> https://jira.sw.ru/browse/PSBM-103727
>> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
>> ---
>>   ipc/mqueue.c | 150 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 150 insertions(+)
>>
>> diff --git a/ipc/mqueue.c b/ipc/mqueue.c
>> index 458e655..48ec6f8 100644
>> --- a/ipc/mqueue.c
>> +++ b/ipc/mqueue.c
>> @@ -35,6 +35,8 @@
>>   #include <linux/ipc_namespace.h>
>>   #include <linux/user_namespace.h>
>>   #include <linux/slab.h>
>> +#include <linux/exportfs.h>
>> +#include <linux/random.h>
>>
>>   #include <net/sock.h>
>>   #include "util.h"
>> @@ -86,6 +88,7 @@ struct mqueue_inode_info {
>>   };
>>
>>   static const struct inode_operations mqueue_dir_inode_operations;
>> +static const struct export_operations mqueue_export_ops;
>>   static const struct file_operations mqueue_file_operations;
>>   static const struct super_operations mqueue_super_ops;
>>   static void remove_notification(struct mqueue_inode_info *info);
>> @@ -117,6 +120,144 @@ static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
>>   	return ns;
>>   }
>>
>> +/*
>> + * hashtable for inodes that have exported fhandles.
>> + * When we export fhandle, we add it's inode into
>> + * hashtable so we can find it fast
>> + */
>> +
>> +#define MQUEUE_INODE_HASH_BITS 7
>
> Why you've chosen smaller hash size than for cgroups?
> #define CGROUP_INODE_HASH_BITS 10
>
>> +static DEFINE_HASHTABLE(mqueue_inode_table, MQUEUE_INODE_HASH_BITS);
>> +static DEFINE_SPINLOCK(mqueue_inode_table_lock);
>> +
>> +struct mq_inode_hitem {
>> +	struct inode *inode;
>> +	struct hlist_node hlist;
>> +};
>> +
>> +static inline unsigned long mqueue_inode_get_hash(unsigned int i_ino)
>> +{
>> +	return hash_32(i_ino, MQUEUE_INODE_HASH_BITS);
>> +}
>> +
>> +static struct mq_inode_hitem *mqueue_find_item_no_lock(unsigned long fh[2])
>> +{
>> +	struct mq_inode_hitem *i;
>> +	struct hlist_head *head = mqueue_inode_table
>> +		+ mqueue_inode_get_hash(fh[1]);
>> +	struct mq_inode_hitem *found = NULL;
>> +
>> +	hlist_for_each_entry(i, head, hlist) {
>> +		if (i->inode->i_generation == fh[0] &&
>> +		    i->inode->i_ino == fh[1]) {
>> +			found = i;
>> +			break;
>> +		}
>> +	}
>> +
>> +	return found;
>> +}
>> +
>> +static struct inode *mqueue_find_inode(unsigned long fh[2], char take_ref)
>> +{
>> +	struct mq_inode_hitem *item;
>> +	struct inode *ret = NULL;
>> +
>> +	spin_lock(&mqueue_inode_table_lock);
>> +	item = mqueue_find_item_no_lock(fh);
>> +	if (item && take_ref && !igrab(item->inode))
>> +		item = NULL;
>> +	spin_unlock(&mqueue_inode_table_lock);
>> +
>> +	if (item)
>> +		ret = item->inode;
>> +
>> +	return ret;
>> +}
>> +
>> +static int mqueue_hash_add(struct inode *inode)
>> +{
>> +	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
>> +
>> +	if (!mqueue_find_inode(fh, 0)) {
>> +		struct mq_inode_hitem *item;
>> +		struct mq_inode_hitem *existing_item = 0;
>> +		struct hlist_head *head = mqueue_inode_table
>> +			+ mqueue_inode_get_hash(inode->i_ino);
>> +
>> +		item = kmalloc(sizeof(struct mq_inode_hitem), GFP_KERNEL);
>> +		if (!item)
>> +			return -ENOMEM;
>> +		item->inode = inode;
>> +
>> +		spin_lock(&mqueue_inode_table_lock);
>> +		existing_item = mqueue_find_item_no_lock(fh);
>> +		if (!existing_item)
>> +			hlist_add_head(&item->hlist, head);
>> +		spin_unlock(&mqueue_inode_table_lock);
>> +
>> +		if (existing_item)
>> +			kfree(item);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void mqueue_hash_del(struct inode *inode)
>> +{
>> +	struct mq_inode_hitem *item;
>> +	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
>> +
>> +	spin_lock(&mqueue_inode_table_lock);
>> +	item = mqueue_find_item_no_lock(fh);
>> +	if (item)
>> +		hlist_del(&item->hlist);
>> +	spin_unlock(&mqueue_inode_table_lock);
>> +
>> +	kfree(item);
>> +	return;
>> +}
>> +
>> +static struct dentry *mqueue_fh_to_dentry(struct super_block *sb,
>> +		struct fid *fid, int fh_len, int fh_type)
>> +{
>> +	struct inode *inode;
>> +	struct dentry *dentry = ERR_PTR(-ENOENT);
>> +	unsigned long fhandle[2] = {fid->raw[0], fid->raw[1]};
>> +
>> +	if (fh_len < 2)
>> +		return NULL;
>> +
>> +	inode = mqueue_find_inode(fhandle, 1);
>> +	if (inode) {
>> +		dentry = d_find_alias(inode);
>> +		iput(inode);
>> +	}
>> +	return dentry;
>> +}
>> +
>> +static int mqueue_encode_fh(struct inode *inode, __u32 *fh, int *len,
>> +				struct inode *parent)
>> +{
>> +	if (*len < 2) {
>> +		*len = 2;
>> +		return FILEID_INVALID;
>> +	}
>> +
>> +	/*
>> +	 * encode_fh is expected to return 255 (FILEID_INVALID)
>> +	 * in case of failure. We can't return ENOMEM, so
>> +	 * return FILEID_INVALID at least.
>> +	 */
>> +	if (mqueue_hash_add(inode))
>> +		return FILEID_INVALID;
>> +
>> +	fh[0] = inode->i_generation;
>> +	fh[1] = inode->i_ino;
>> +	*len = 2;
>> +	return 1;
>> +}
>> +
>>   /* Auxiliary functions to manipulate messages' list */
>>   static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
>>   {
>> @@ -226,6 +367,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
>>   		goto err;
>>
>>   	inode->i_ino = get_next_ino();
>> +	inode->i_generation = prandom_u32();
>>   	inode->i_mode = mode;
>>   	inode->i_uid = current_fsuid();
>>   	inode->i_gid = current_fsgid();
>> @@ -316,6 +458,7 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
>>   	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
>>   	sb->s_magic = MQUEUE_MAGIC;
>>   	sb->s_op = &mqueue_super_ops;
>> +	sb->s_export_op = &mqueue_export_ops;
>>
>>   	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
>>   	if (IS_ERR(inode))
>> @@ -382,6 +525,8 @@ static void mqueue_evict_inode(struct inode *inode)
>>   	if (S_ISDIR(inode->i_mode))
>>   		return;
>>
>> +	mqueue_hash_del(inode);
>> +
>
> Looks like for cgroups we should've also put cgroup_hash_del to
> ->evict_inode helper, to be able to use igrab in cgroup_find_inode.
> Shouldn't we?
>
>>   	ipc_ns = get_ns_from_inode(inode);
>>   	info = MQUEUE_I(inode);
>>   	spin_lock(&info->lock);
>> @@ -1376,6 +1521,11 @@ static const struct inode_operations mqueue_dir_inode_operations = {
>>   	.unlink = mqueue_unlink,
>>   };
>>
>> +static const struct export_operations mqueue_export_ops = {
>> +	.encode_fh      = mqueue_encode_fh,
>> +	.fh_to_dentry	= mqueue_fh_to_dentry,
>> +};
>> +
>>   static const struct file_operations mqueue_file_operations = {
>>   	.flush = mqueue_flush_file,
>>   	.poll = mqueue_poll_file,
>>
>
Andrey Zhadchenko Sept. 24, 2020, 1:18 p.m.
For some reason i have forgotten to send a copy to devel@openvz.org
during this conversation
Highlits:
>>>> +
>>>> +#define MQUEUE_INODE_HASH_BITS 7  
>>>
>>> Why you've chosen smaller hash size than for cgroups?
>>> #define CGROUP_INODE_HASH_BITS 10
>>>  
>> 
>> I think inotify on mqueue mount is quite rare. It doesn't look like
>> something default as inotify on cgroup for kubernetes.  
>
>OK.

>>>> +	mqueue_hash_del(inode);
>>>> +  
>>>
>>> Looks like for cgroups we should've also put cgroup_hash_del to  
>>> ->evict_inode helper, to be able to use igrab in
>>> cgroup_find_inode.  
>>> Shouldn't we?
>>>  
>> 
>> This is very good idea, looks more robust. I should make a patch.  
>
>Nice!


On Thu, 24 Sep 2020 13:38:24 +0300
Konstantin Khorenko <khorenko@virtuozzo.com> wrote:

> On 09/09/2020 01:19 PM, Pavel Tikhomirov wrote:
> > Looks good.
> >
> > Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
> >
> > But please also see two non-critical questions below.  
> 
> Andrey, any answer on that?
> 
> 
> > On 9/8/20 5:33 PM, Andrey Zhadchenko wrote:  
> >> criu uses fhandle from fdinfo to dump inotify objects, but mqueue
> >> has no export_operations in super block. However, they are needed
> >> if we want to operate with files using fhandles.
> >> Add hash table as a storage for exported inodes.
> >>
> >> https://jira.sw.ru/browse/PSBM-103727
> >> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
> >> ---
> >>   ipc/mqueue.c | 150
> >> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file
> >> changed, 150 insertions(+)
> >>
> >> diff --git a/ipc/mqueue.c b/ipc/mqueue.c
> >> index 458e655..48ec6f8 100644
> >> --- a/ipc/mqueue.c
> >> +++ b/ipc/mqueue.c
> >> @@ -35,6 +35,8 @@
> >>   #include <linux/ipc_namespace.h>
> >>   #include <linux/user_namespace.h>
> >>   #include <linux/slab.h>
> >> +#include <linux/exportfs.h>
> >> +#include <linux/random.h>
> >>
> >>   #include <net/sock.h>
> >>   #include "util.h"
> >> @@ -86,6 +88,7 @@ struct mqueue_inode_info {
> >>   };
> >>
> >>   static const struct inode_operations mqueue_dir_inode_operations;
> >> +static const struct export_operations mqueue_export_ops;
> >>   static const struct file_operations mqueue_file_operations;
> >>   static const struct super_operations mqueue_super_ops;
> >>   static void remove_notification(struct mqueue_inode_info *info);
> >> @@ -117,6 +120,144 @@ static struct ipc_namespace
> >> *get_ns_from_inode(struct inode *inode) return ns;
> >>   }
> >>
> >> +/*
> >> + * hashtable for inodes that have exported fhandles.
> >> + * When we export fhandle, we add it's inode into
> >> + * hashtable so we can find it fast
> >> + */
> >> +
> >> +#define MQUEUE_INODE_HASH_BITS 7  
> >
> > Why you've chosen smaller hash size than for cgroups?
> > #define CGROUP_INODE_HASH_BITS 10
> >  
> >> +static DEFINE_HASHTABLE(mqueue_inode_table,
> >> MQUEUE_INODE_HASH_BITS); +static
> >> DEFINE_SPINLOCK(mqueue_inode_table_lock); +
> >> +struct mq_inode_hitem {
> >> +	struct inode *inode;
> >> +	struct hlist_node hlist;
> >> +};
> >> +
> >> +static inline unsigned long mqueue_inode_get_hash(unsigned int
> >> i_ino) +{
> >> +	return hash_32(i_ino, MQUEUE_INODE_HASH_BITS);
> >> +}
> >> +
> >> +static struct mq_inode_hitem *mqueue_find_item_no_lock(unsigned
> >> long fh[2]) +{
> >> +	struct mq_inode_hitem *i;
> >> +	struct hlist_head *head = mqueue_inode_table
> >> +		+ mqueue_inode_get_hash(fh[1]);
> >> +	struct mq_inode_hitem *found = NULL;
> >> +
> >> +	hlist_for_each_entry(i, head, hlist) {
> >> +		if (i->inode->i_generation == fh[0] &&
> >> +		    i->inode->i_ino == fh[1]) {
> >> +			found = i;
> >> +			break;
> >> +		}
> >> +	}
> >> +
> >> +	return found;
> >> +}
> >> +
> >> +static struct inode *mqueue_find_inode(unsigned long fh[2], char
> >> take_ref) +{
> >> +	struct mq_inode_hitem *item;
> >> +	struct inode *ret = NULL;
> >> +
> >> +	spin_lock(&mqueue_inode_table_lock);
> >> +	item = mqueue_find_item_no_lock(fh);
> >> +	if (item && take_ref && !igrab(item->inode))
> >> +		item = NULL;
> >> +	spin_unlock(&mqueue_inode_table_lock);
> >> +
> >> +	if (item)
> >> +		ret = item->inode;
> >> +
> >> +	return ret;
> >> +}
> >> +
> >> +static int mqueue_hash_add(struct inode *inode)
> >> +{
> >> +	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
> >> +
> >> +	if (!mqueue_find_inode(fh, 0)) {
> >> +		struct mq_inode_hitem *item;
> >> +		struct mq_inode_hitem *existing_item = 0;
> >> +		struct hlist_head *head = mqueue_inode_table
> >> +			+ mqueue_inode_get_hash(inode->i_ino);
> >> +
> >> +		item = kmalloc(sizeof(struct mq_inode_hitem),
> >> GFP_KERNEL);
> >> +		if (!item)
> >> +			return -ENOMEM;
> >> +		item->inode = inode;
> >> +
> >> +		spin_lock(&mqueue_inode_table_lock);
> >> +		existing_item = mqueue_find_item_no_lock(fh);
> >> +		if (!existing_item)
> >> +			hlist_add_head(&item->hlist, head);
> >> +		spin_unlock(&mqueue_inode_table_lock);
> >> +
> >> +		if (existing_item)
> >> +			kfree(item);
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void mqueue_hash_del(struct inode *inode)
> >> +{
> >> +	struct mq_inode_hitem *item;
> >> +	unsigned long fh[2] = {inode->i_generation, inode->i_ino};
> >> +
> >> +	spin_lock(&mqueue_inode_table_lock);
> >> +	item = mqueue_find_item_no_lock(fh);
> >> +	if (item)
> >> +		hlist_del(&item->hlist);
> >> +	spin_unlock(&mqueue_inode_table_lock);
> >> +
> >> +	kfree(item);
> >> +	return;
> >> +}
> >> +
> >> +static struct dentry *mqueue_fh_to_dentry(struct super_block *sb,
> >> +		struct fid *fid, int fh_len, int fh_type)
> >> +{
> >> +	struct inode *inode;
> >> +	struct dentry *dentry = ERR_PTR(-ENOENT);
> >> +	unsigned long fhandle[2] = {fid->raw[0], fid->raw[1]};
> >> +
> >> +	if (fh_len < 2)
> >> +		return NULL;
> >> +
> >> +	inode = mqueue_find_inode(fhandle, 1);
> >> +	if (inode) {
> >> +		dentry = d_find_alias(inode);
> >> +		iput(inode);
> >> +	}
> >> +	return dentry;
> >> +}
> >> +
> >> +static int mqueue_encode_fh(struct inode *inode, __u32 *fh, int
> >> *len,
> >> +				struct inode *parent)
> >> +{
> >> +	if (*len < 2) {
> >> +		*len = 2;
> >> +		return FILEID_INVALID;
> >> +	}
> >> +
> >> +	/*
> >> +	 * encode_fh is expected to return 255 (FILEID_INVALID)
> >> +	 * in case of failure. We can't return ENOMEM, so
> >> +	 * return FILEID_INVALID at least.
> >> +	 */
> >> +	if (mqueue_hash_add(inode))
> >> +		return FILEID_INVALID;
> >> +
> >> +	fh[0] = inode->i_generation;
> >> +	fh[1] = inode->i_ino;
> >> +	*len = 2;
> >> +	return 1;
> >> +}
> >> +
> >>   /* Auxiliary functions to manipulate messages' list */
> >>   static int msg_insert(struct msg_msg *msg, struct
> >> mqueue_inode_info *info) {
> >> @@ -226,6 +367,7 @@ static struct inode *mqueue_get_inode(struct
> >> super_block *sb, goto err;
> >>
> >>   	inode->i_ino = get_next_ino();
> >> +	inode->i_generation = prandom_u32();
> >>   	inode->i_mode = mode;
> >>   	inode->i_uid = current_fsuid();
> >>   	inode->i_gid = current_fsgid();
> >> @@ -316,6 +458,7 @@ static int mqueue_fill_super(struct
> >> super_block *sb, void *data, int silent) sb->s_blocksize_bits =
> >> PAGE_CACHE_SHIFT; sb->s_magic = MQUEUE_MAGIC;
> >>   	sb->s_op = &mqueue_super_ops;
> >> +	sb->s_export_op = &mqueue_export_ops;
> >>
> >>   	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX |
> >> S_IRWXUGO, NULL); if (IS_ERR(inode))
> >> @@ -382,6 +525,8 @@ static void mqueue_evict_inode(struct inode
> >> *inode) if (S_ISDIR(inode->i_mode))
> >>   		return;
> >>
> >> +	mqueue_hash_del(inode);
> >> +  
> >
> > Looks like for cgroups we should've also put cgroup_hash_del to  
> > ->evict_inode helper, to be able to use igrab in
> > cgroup_find_inode. Shouldn't we?
> >  
> >>   	ipc_ns = get_ns_from_inode(inode);
> >>   	info = MQUEUE_I(inode);
> >>   	spin_lock(&info->lock);
> >> @@ -1376,6 +1521,11 @@ static const struct inode_operations
> >> mqueue_dir_inode_operations = { .unlink = mqueue_unlink,
> >>   };
> >>
> >> +static const struct export_operations mqueue_export_ops = {
> >> +	.encode_fh      = mqueue_encode_fh,
> >> +	.fh_to_dentry	= mqueue_fh_to_dentry,
> >> +};
> >> +
> >>   static const struct file_operations mqueue_file_operations = {
> >>   	.flush = mqueue_flush_file,
> >>   	.poll = mqueue_poll_file,
> >>  
> >