[PATCH] shm: Fix the filename of hugetlb sysv shared memory

Eric W. Biederman
2007-06-08T23:43:34Z

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>
---
fs/hugetlbfs/inode.c | 7 ++-----
include/linux/hugetlb.h | 4 ++--
ipc/shm.c | 6 +++---
3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index aa083dd..e6b46b3 100644
--- 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 b4570b6..2c13715 100644
--- 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 4fefbad..c31f743 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -364,9 +364,10 @@ 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;
@@ -377,7 +378,6 @@ 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);
--
1.5.1.1.181.g2de0