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| author | Miklos Szeredi <mszeredi@suse.cz> | 2008-03-26 22:11:34 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2008-04-23 00:04:45 -0400 |
| commit | 73cd49ecdde92fdce131938bdaff4993010d181b (patch) | |
| tree | 90c9cd3597a915c1f820a3cd1fde1689e9a7ab1f | |
| parent | 9d1bc60138977d9c79471b344a64f2df13b2ccef (diff) | |
| download | linux-73cd49ecdde92fdce131938bdaff4993010d181b.tar.gz linux-73cd49ecdde92fdce131938bdaff4993010d181b.tar.bz2 linux-73cd49ecdde92fdce131938bdaff4993010d181b.zip | |
[patch 3/7] vfs: mountinfo: add mount ID
Add a unique ID to each vfsmount using the IDR infrastructure. The
identifiers are reused after the vfsmount is freed.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/namespace.c | 34 | ||||
| -rw-r--r-- | include/linux/mount.h | 1 |
2 files changed, 35 insertions, 0 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 1bf302d0478b..8ca6317cb401 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -27,6 +27,7 @@ #include <linux/mount.h> #include <linux/ramfs.h> #include <linux/log2.h> +#include <linux/idr.h> #include <asm/uaccess.h> #include <asm/unistd.h> #include "pnode.h" @@ -39,6 +40,7 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); static int event; +static DEFINE_IDA(mnt_id_ida); static struct list_head *mount_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; @@ -58,10 +60,41 @@ static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) +/* allocation is serialized by namespace_sem */ +static int mnt_alloc_id(struct vfsmount *mnt) +{ + int res; + +retry: + ida_pre_get(&mnt_id_ida, GFP_KERNEL); + spin_lock(&vfsmount_lock); + res = ida_get_new(&mnt_id_ida, &mnt->mnt_id); + spin_unlock(&vfsmount_lock); + if (res == -EAGAIN) + goto retry; + + return res; +} + +static void mnt_free_id(struct vfsmount *mnt) +{ + spin_lock(&vfsmount_lock); + ida_remove(&mnt_id_ida, mnt->mnt_id); + spin_unlock(&vfsmount_lock); +} + struct vfsmount *alloc_vfsmnt(const char *name) { struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); if (mnt) { + int err; + + err = mnt_alloc_id(mnt); + if (err) { + kmem_cache_free(mnt_cache, mnt); + return NULL; + } + atomic_set(&mnt->mnt_count, 1); INIT_LIST_HEAD(&mnt->mnt_hash); INIT_LIST_HEAD(&mnt->mnt_child); @@ -353,6 +386,7 @@ EXPORT_SYMBOL(simple_set_mnt); void free_vfsmnt(struct vfsmount *mnt) { kfree(mnt->mnt_devname); + mnt_free_id(mnt); kmem_cache_free(mnt_cache, mnt); } diff --git a/include/linux/mount.h b/include/linux/mount.h index 87b24cea1863..f0dfb17ffccc 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -56,6 +56,7 @@ struct vfsmount { struct list_head mnt_slave; /* slave list entry */ struct vfsmount *mnt_master; /* slave is on master->mnt_slave_list */ struct mnt_namespace *mnt_ns; /* containing namespace */ + int mnt_id; /* mount identifier */ /* * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount * to let these frequently modified fields in a separate cache line |