shm: fix the filename of hugetlb sysv shared memory

Some user space tools need to identify SYSV shared memory when examining
/proc/<pid>/maps.  To do so they look for a block device with major zero, a
dentry named SYSV<sysv key>, and having the minor of the internal sysv
shared memory kernel mount.

To help these tools and to make it easier for people just browsing
/proc/<pid>/maps this patch modifies hugetlb sysv shared memory to use the
SYSV<key> dentry naming convention.

User space tools will still have to be aware that hugetlb sysv shared
memory lives on a different internal kernel mount and so has a different
block device minor number from the rest of sysv shared memory.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Albert Cahalan <acahalan@gmail.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index aa083dd34e924199816587d57861d48dfa84dbfe..e6b46b3ac2fe6b6402502b0f0bda2c84400ceb94 100644 (file)
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -736,15 +736,13 @@ static int can_do_hugetlb_shm(void)
                        can_do_mlock());
 }
 
-struct file *hugetlb_zero_setup(size_t size)
+struct file *hugetlb_file_setup(const char *name, size_t size)
 {
        int error = -ENOMEM;
        struct file *file;
        struct inode *inode;
        struct dentry *dentry, *root;
        struct qstr quick_string;
-       char buf[16];
-       static atomic_t counter;
 
        if (!hugetlbfs_vfsmount)
                return ERR_PTR(-ENOENT);
@@ -756,8 +754,7 @@ struct file *hugetlb_zero_setup(size_t size)
                return ERR_PTR(-ENOMEM);
 
        root = hugetlbfs_vfsmount->mnt_root;
-       snprintf(buf, 16, "%u", atomic_inc_return(&counter));
-       quick_string.name = buf;
+       quick_string.name = name;
        quick_string.len = strlen(quick_string.name);
        quick_string.hash = 0;
        dentry = d_alloc(root, &quick_string);

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index b4570b62ab8557d9748f7887b878bb341b87c553..2c13715e9ddea9f643c6a66c613ffcabee091f1c 100644 (file)
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -163,7 +163,7 @@ static inline struct hugetlbfs_sb_info *HUGETLBFS_SB(struct super_block *sb)
 
 extern const struct file_operations hugetlbfs_file_operations;
 extern struct vm_operations_struct hugetlb_vm_ops;
-struct file *hugetlb_zero_setup(size_t);
+struct file *hugetlb_file_setup(const char *name, size_t);
 int hugetlb_get_quota(struct address_space *mapping);
 void hugetlb_put_quota(struct address_space *mapping);
 
@@ -185,7 +185,7 @@ static inline void set_file_hugepages(struct file *file)
 
 #define is_file_hugepages(file)                0
 #define set_file_hugepages(file)       BUG()
-#define hugetlb_zero_setup(size)       ERR_PTR(-ENOSYS)
+#define hugetlb_file_setup(name,size)  ERR_PTR(-ENOSYS)
 
 #endif /* !CONFIG_HUGETLBFS */
 

diff --git a/ipc/shm.c b/ipc/shm.c
index 047b823e6bf0e3b2639bfb81958f658404cc70b8..0852f206d8951cb4f53071b36e159ae0332e5093 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -366,9 +366,10 @@ static int newseg (struct ipc_namespace *ns, key_t key, int shmflg, size_t size)
                return error;
        }
 
+       sprintf (name, "SYSV%08x", key);
        if (shmflg & SHM_HUGETLB) {
-               /* hugetlb_zero_setup takes care of mlock user accounting */
-               file = hugetlb_zero_setup(size);
+               /* hugetlb_file_setup takes care of mlock user accounting */
+               file = hugetlb_file_setup(name, size);
                shp->mlock_user = current->user;
        } else {
                int acctflag = VM_ACCOUNT;
@@ -379,7 +380,6 @@ static int newseg (struct ipc_namespace *ns, key_t key, int shmflg, size_t size)
                if  ((shmflg & SHM_NORESERVE) &&
                                sysctl_overcommit_memory != OVERCOMMIT_NEVER)
                        acctflag = 0;
-               sprintf (name, "SYSV%08x", key);
                file = shmem_file_setup(name, size, acctflag);
        }
        error = PTR_ERR(file);