This patch is not needed for vz8, because cgroup will use kernfs, which has export_operations implemented.
Best regards, Andrey Zhadchenko On Thu, 24 Sep 2020 10:41:31 +0300 Konstantin Khorenko <khore...@virtuozzo.com> wrote: > Please, port this patch to vz8 as well, branch > branch-rh8-4.18.0-193.6.3.vz8.4.x-ovz > > -- > Best regards, > > Konstantin Khorenko, > Virtuozzo Linux Kernel Team > > On 07/30/2020 04:01 PM, Andrey Zhadchenko wrote: > > criu uses fhandle from fdinfo to dump inotify objects. cgroup super > > block has no export operations, but .encode_fh and .fh_to_dentry > > are needed for inotify_fdinfo function and open_by_handle_at > > syscall in order to correctly open files located on cgroupfs by > > fhandle. Add hash table as a storage for inodes with exported > > fhandle. > > > > v3: use inode->i_gen to protect from i_ino reusage. increase > > fhandle size to 2 * u32. > > Add an option to take reference of inode in cgroup_find_inode, so > > no one can delete recently found inode. > > v4: introduced hashtable helper functions to avoid races. > > changed i_gen generation from get_seconds to prandom_u32. > > > > https://jira.sw.ru/browse/PSBM-105889 > > Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com> > > --- > > kernel/cgroup.c | 168 > > +++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file > > changed, 167 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > > index 9fdba79..956a9ac 100644 > > --- a/kernel/cgroup.c > > +++ b/kernel/cgroup.c > > @@ -62,6 +62,8 @@ > > #include <linux/kthread.h> > > #include <linux/ve.h> > > #include <linux/stacktrace.h> > > +#include <linux/exportfs.h> > > +#include <linux/random.h> > > > > #include <linux/atomic.h> > > > > @@ -765,6 +767,7 @@ static struct inode *cgroup_new_inode(umode_t > > mode, struct super_block *sb) > > > > if (inode) { > > 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(); > > @@ -1390,9 +1393,171 @@ out: > > } > > #endif > > > > +/* > > + * 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 CGROUP_INODE_HASH_BITS 10 > > +static DEFINE_HASHTABLE(cgroup_inode_table, > > CGROUP_INODE_HASH_BITS); +static > > DEFINE_SPINLOCK(cgroup_inode_table_lock); + > > +struct cg_inode_hitem { > > + struct inode *inode; > > + struct hlist_node hlist; > > +}; > > + > > +static inline unsigned long cgroup_inode_get_hash(unsigned int > > i_ino) +{ > > + return hash_32(i_ino, CGROUP_INODE_HASH_BITS); > > +} > > + > > +static struct cg_inode_hitem *cgroup_find_item_no_lock(unsigned > > long fh[2]) +{ > > + struct cg_inode_hitem *i; > > + struct hlist_head *head = cgroup_inode_table > > + + cgroup_inode_get_hash(fh[1]); > > + struct cg_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 *cgroup_find_inode(unsigned long fh[2], char > > take_ref) +{ > > + struct cg_inode_hitem *item; > > + struct inode *ret = NULL; > > + > > + spin_lock(&cgroup_inode_table_lock); > > + item = cgroup_find_item_no_lock(fh); > > + > > + /* > > + * If we need to increase refcount, we should be aware of > > possible > > + * deadlock. Another thread may have started deleting this > > inode: > > + * iput->iput_final->cgroup_delete_inode->cgroup_hash_del > > + * If we just call igrab, it will try to take i_lock and > > this will > > + * result in deadlock, because deleting thread has already > > taken it > > + * and waits on cgroup_inode_table_lock to find inode in > > hashtable. > > + * > > + * If i_count is zero, someone is deleting it -> skip. > > + */ > > + if (take_ref && item) > > + if (!atomic_inc_not_zero(&item->inode->i_count)) > > + item = NULL; > > + > > + spin_unlock(&cgroup_inode_table_lock); > > + > > + if (item) > > + ret = item->inode; > > + > > + return ret; > > +} > > + > > +static int cgroup_hash_add(struct inode *inode) > > +{ > > + unsigned long fh[2] = {inode->i_generation, inode->i_ino}; > > + > > + if (!cgroup_find_inode(fh, 0)) { > > + struct cg_inode_hitem *item; > > + struct cg_inode_hitem *existing_item = 0; > > + struct hlist_head *head = cgroup_inode_table > > + + cgroup_inode_get_hash(inode->i_ino); > > + > > + item = kmalloc(sizeof(struct cg_inode_hitem), > > GFP_KERNEL); > > + if (!item) > > + return -ENOMEM; > > + item->inode = inode; > > + > > + spin_lock(&cgroup_inode_table_lock); > > + existing_item = cgroup_find_item_no_lock(fh); > > + if (!existing_item) > > + hlist_add_head(&item->hlist, head); > > + spin_unlock(&cgroup_inode_table_lock); > > + > > + if (existing_item) > > + kfree(item); > > + } > > + > > + return 0; > > +} > > + > > +static void cgroup_hash_del(struct inode *inode) > > +{ > > + struct cg_inode_hitem *item; > > + unsigned long fh[2] = {inode->i_generation, inode->i_ino}; > > + > > + spin_lock(&cgroup_inode_table_lock); > > + item = cgroup_find_item_no_lock(fh); > > + if (item) > > + hlist_del(&item->hlist); > > + spin_unlock(&cgroup_inode_table_lock); > > + > > + kfree(item); > > + return; > > +} > > + > > +static struct dentry *cgroup_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 = cgroup_find_inode(fhandle, 1); > > + if (inode) { > > + dentry = d_find_alias(inode); > > + iput(inode); > > + } > > + return dentry; > > +} > > + > > +static int cgroup_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 (cgroup_hash_add(inode)) > > + return FILEID_INVALID; > > + > > + fh[0] = inode->i_generation; > > + fh[1] = inode->i_ino; > > + *len = 2; > > + return 1; > > +} > > + > > +static const struct export_operations cgroup_export_ops = { > > + .encode_fh = cgroup_encode_fh, > > + .fh_to_dentry = cgroup_fh_to_dentry, > > +}; > > + > > +static int cgroup_delete_inode(struct inode *inode) > > +{ > > + cgroup_hash_del(inode); > > + return generic_delete_inode(inode); > > +} > > + > > static const struct super_operations cgroup_ops = { > > .statfs = simple_statfs, > > - .drop_inode = generic_delete_inode, > > + .drop_inode = cgroup_delete_inode, > > .show_options = cgroup_show_options, > > #ifdef CONFIG_VE > > .show_path = cgroup_show_path, > > @@ -1539,6 +1704,7 @@ static int cgroup_set_super(struct > > super_block *sb, void *data) sb->s_blocksize_bits = > > PAGE_CACHE_SHIFT; sb->s_magic = CGROUP_SUPER_MAGIC; > > sb->s_op = &cgroup_ops; > > + sb->s_export_op = &cgroup_export_ops; > > > > return 0; > > } > > _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
