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Commit 9d66586f authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
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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: default avatarEric 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 22741925

fs/hugetlbfs/inode.c

+2 −5
Original line number Diff line number Diff line
@@ -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);

include/linux/hugetlb.h

+2 −2
Original line number Diff line number Diff line
@@ -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 */

ipc/shm.c

+3 −3
Original line number Diff line number Diff line
@@ -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);