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Mon, 11 Apr 2022 16:06:50 +0000 Received: from BN8PR10MB3220.namprd10.prod.outlook.com ([fe80::41da:48ff:402:1a40]) by BN8PR10MB3220.namprd10.prod.outlook.com ([fe80::41da:48ff:402:1a40%6]) with mapi id 15.20.5144.029; Mon, 11 Apr 2022 16:06:49 +0000 From: Khalid Aziz To: akpm@linux-foundation.org, willy@infradead.org Cc: Khalid Aziz , aneesh.kumar@linux.ibm.com, arnd@arndb.de, 21cnbao@gmail.com, corbet@lwn.net, dave.hansen@linux.intel.com, david@redhat.com, ebiederm@xmission.com, hagen@jauu.net, jack@suse.cz, keescook@chromium.org, kirill@shutemov.name, kucharsk@gmail.com, linkinjeon@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, longpeng2@huawei.com, luto@kernel.org, markhemm@googlemail.com, pcc@google.com, rppt@kernel.org, sieberf@amazon.com, sjpark@amazon.de, surenb@google.com, tst@schoebel-theuer.de, yzaikin@google.com Subject: [PATCH v1 03/14] mm/mshare: Add read for msharefs Date: Mon, 11 Apr 2022 10:05:47 -0600 Message-Id: <4978f8cd6e566e531af457d46d00e5a7f3b2d8df.1649370874.git.khalid.aziz@oracle.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: References: Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: SJ0P220CA0013.NAMP220.PROD.OUTLOOK.COM (2603:10b6:a03:41b::20) To BN8PR10MB3220.namprd10.prod.outlook.com (2603:10b6:408:c8::18) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9d1590be-639b-4853-c05e-08da1bd54921 X-MS-TrafficTypeDiagnostic: CO1PR10MB4564:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Add a read operation to file created by mshare syscall to return the starting address and size of region shared by the corresponding range. This information is returned as struct mshare_info defined in include/uapi/linux/mman.h Signed-off-by: Khalid Aziz --- v1: - Read returns struct instead of two unsigned long (suggested by Mike Rapoport) include/uapi/linux/mman.h | 5 +++ mm/mshare.c | 68 ++++++++++++++++++++++++++++++++++++--- 2 files changed, 68 insertions(+), 5 deletions(-) diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h index f55bc680b5b0..56fe446e24b1 100644 --- a/include/uapi/linux/mman.h +++ b/include/uapi/linux/mman.h @@ -41,4 +41,9 @@ #define MAP_HUGE_2GB HUGETLB_FLAG_ENCODE_2GB #define MAP_HUGE_16GB HUGETLB_FLAG_ENCODE_16GB +struct mshare_info { + unsigned long start; + unsigned long size; +}; + #endif /* _UAPI_LINUX_MMAN_H */ diff --git a/mm/mshare.c b/mm/mshare.c index ad695288d4bb..59e5d294e562 100644 --- a/mm/mshare.c +++ b/mm/mshare.c @@ -16,14 +16,39 @@ #include #include #include +#include +#include #include #include +#include + +struct mshare_data { + struct mm_struct *mm; + refcount_t refcnt; +}; static struct super_block *msharefs_sb; +static ssize_t +mshare_read(struct kiocb *iocb, struct iov_iter *iov) +{ + struct mshare_data *info = iocb->ki_filp->private_data; + struct mm_struct *mm = info->mm; + size_t ret; + struct mshare_info m_info; + + m_info.start = mm->mmap_base; + m_info.size = mm->task_size - mm->mmap_base; + ret = copy_to_iter(&m_info, sizeof(m_info), iov); + if (!ret) + return -EFAULT; + return ret; +} + static const struct file_operations msharefs_file_operations = { - .open = simple_open, - .llseek = no_llseek, + .open = simple_open, + .read_iter = mshare_read, + .llseek = no_llseek, }; static int @@ -77,7 +102,12 @@ static struct inode inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); inode->i_fop = &msharefs_file_operations; - inode->i_size = 0; + + /* + * A read from this file will return two unsigned long + */ + inode->i_size = 2 * sizeof(unsigned long); + inode->i_uid = current_fsuid(); inode->i_gid = current_fsgid(); } @@ -86,7 +116,8 @@ static struct inode } static int -mshare_file_create(const char *name, unsigned long flags) +mshare_file_create(const char *name, unsigned long flags, + struct mshare_data *info) { struct inode *inode; struct dentry *root, *dentry; @@ -98,6 +129,8 @@ mshare_file_create(const char *name, unsigned long flags) if (IS_ERR(inode)) return PTR_ERR(inode); + inode->i_private = info; + dentry = msharefs_alloc_dentry(root, name); if (IS_ERR(dentry)) { err = PTR_ERR(dentry); @@ -120,6 +153,8 @@ SYSCALL_DEFINE5(mshare, const char __user *, name, unsigned long, addr, unsigned long, len, int, oflag, mode_t, mode) { char mshare_name[NAME_MAX]; + struct mshare_data *info; + struct mm_struct *mm; int err; /* @@ -133,8 +168,31 @@ SYSCALL_DEFINE5(mshare, const char __user *, name, unsigned long, addr, if (err) goto err_out; - err = mshare_file_create(mshare_name, oflag); + mm = mm_alloc(); + if (!mm) + return -ENOMEM; + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (!info) { + err = -ENOMEM; + goto err_relmm; + } + mm->mmap_base = addr; + mm->task_size = addr + len; + if (!mm->task_size) + mm->task_size--; + info->mm = mm; + refcount_set(&info->refcnt, 1); + + err = mshare_file_create(mshare_name, oflag, info); + if (err) + goto err_relinfo; + + return 0; +err_relinfo: + kfree(info); +err_relmm: + mmput(mm); err_out: return err; } -- 2.32.0