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    SubjectRe: [PATCH 1/2] proc: Generalize proc inode allocation
    Quoting Eric W. Biederman (ebiederm@xmission.com):
    >
    > Generalize the proc inode allocation so that it can be
    > used without having to having to create a proc_dir_entry.
    >
    > This will allow namespace file descriptors to remain light
    > weight entitities but still have the same inode number
    > when the backing namespace is the same.
    >
    > Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

    Acked-by: Serge Hallyn <serge@hallyn.com>

    > ---
    >
    > Baring problems in review I plan to merge these patches
    > via my linux-2.6-nsfd tree.
    >
    > fs/proc/generic.c | 26 +++++++++++++-------------
    > include/linux/proc_fs.h | 10 ++++++++++
    > 2 files changed, 23 insertions(+), 13 deletions(-)
    >
    > diff --git a/fs/proc/generic.c b/fs/proc/generic.c
    > index f1637f1..65416a1 100644
    > --- a/fs/proc/generic.c
    > +++ b/fs/proc/generic.c
    > @@ -350,14 +350,14 @@ static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
    > * Return an inode number between PROC_DYNAMIC_FIRST and
    > * 0xffffffff, or zero on failure.
    > */
    > -static unsigned int get_inode_number(void)
    > +int proc_alloc_inum(unsigned int *inum)
    > {
    > unsigned int i;
    > int error;
    >
    > retry:
    > - if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0)
    > - return 0;
    > + if (!ida_pre_get(&proc_inum_ida, GFP_KERNEL))
    > + return -ENOMEM;
    >
    > spin_lock(&proc_inum_lock);
    > error = ida_get_new(&proc_inum_ida, &i);
    > @@ -365,18 +365,19 @@ retry:
    > if (error == -EAGAIN)
    > goto retry;
    > else if (error)
    > - return 0;
    > + return error;
    >
    > if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
    > spin_lock(&proc_inum_lock);
    > ida_remove(&proc_inum_ida, i);
    > spin_unlock(&proc_inum_lock);
    > - return 0;
    > + return -ENOSPC;
    > }
    > - return PROC_DYNAMIC_FIRST + i;
    > + *inum = PROC_DYNAMIC_FIRST + i;
    > + return 0;
    > }
    >
    > -static void release_inode_number(unsigned int inum)
    > +void proc_free_inum(unsigned int inum)
    > {
    > spin_lock(&proc_inum_lock);
    > ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
    > @@ -554,13 +555,12 @@ static const struct inode_operations proc_dir_inode_operations = {
    >
    > static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
    > {
    > - unsigned int i;
    > struct proc_dir_entry *tmp;
    > + int ret;
    >
    > - i = get_inode_number();
    > - if (i == 0)
    > - return -EAGAIN;
    > - dp->low_ino = i;
    > + ret = proc_alloc_inum(&dp->low_ino);
    > + if (ret)
    > + return ret;
    >
    > if (S_ISDIR(dp->mode)) {
    > if (dp->proc_iops == NULL) {
    > @@ -766,7 +766,7 @@ EXPORT_SYMBOL(proc_create_data);
    >
    > static void free_proc_entry(struct proc_dir_entry *de)
    > {
    > - release_inode_number(de->low_ino);
    > + proc_free_inum(de->low_ino);
    >
    > if (S_ISLNK(de->mode))
    > kfree(de->data);
    > diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
    > index e7576cf..3067b44 100644
    > --- a/include/linux/proc_fs.h
    > +++ b/include/linux/proc_fs.h
    > @@ -175,6 +175,8 @@ extern struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
    >
    > extern struct file *proc_ns_fget(int fd);
    >
    > +extern int proc_alloc_inum(unsigned int *pino);
    > +extern void proc_free_inum(unsigned int inum);
    > #else
    >
    > #define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; })
    > @@ -229,6 +231,14 @@ static inline struct file *proc_ns_fget(int fd)
    > return ERR_PTR(-EINVAL);
    > }
    >
    > +static inline int proc_alloc_inum(unsigned int *inum)
    > +{
    > + *inum = 1;
    > + return 0;
    > +}
    > +static inline void proc_free_inum(unsigned int inum)
    > +{
    > +}
    > #endif /* CONFIG_PROC_FS */
    >
    > #if !defined(CONFIG_PROC_KCORE)
    > --
    > 1.7.5.1.217.g4e3aa
    >


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