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Message-ID: <CAHO5Pa3iZ0ZvNN5ovXmFK4E7PvT-RF64tCBaEPH87zzqNoU4qQ@mail.gmail.com>
Date: Tue, 29 Jul 2014 10:20:59 +0200
From: Michael Kerrisk <mtk.manpages@...il.com>
To: Abhi Das <adas@...hat.com>
Cc: Linux Kernel <linux-kernel@...r.kernel.org>,
Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
cluster-devel@...hat.com, Linux API <linux-api@...r.kernel.org>
Subject: Re: [RFC PATCH 2/5] fs: Add xgetdents system call and xreaddir file operation
[CC += linux-api]
On Fri, Jul 25, 2014 at 7:38 PM, Abhi Das <adas@...hat.com> wrote:
> Also add linux_xdirent structure that will be the container for
> dirent, stat and xattr info.
>
> Signed-off-by: Abhi Das <adas@...hat.com>
> ---
> arch/x86/syscalls/syscall_32.tbl | 1 +
> arch/x86/syscalls/syscall_64.tbl | 1 +
> fs/readdir.c | 42 ++++++++++++++++++++++++++++++++++++++++
> fs/stat.c | 4 +++-
> include/linux/fs.h | 1 +
> include/linux/stat.h | 2 ++
> include/uapi/linux/stat.h | 33 +++++++++++++++++++++++++++++++
> 7 files changed, 83 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
> index 6d6ca37..35723e3 100644
> --- a/arch/x86/syscalls/syscall_32.tbl
> +++ b/arch/x86/syscalls/syscall_32.tbl
> @@ -362,3 +362,4 @@
> 353 i386 renameat2 sys_renameat2
> 354 i386 xstat sys_xstat
> 355 i386 fxstat sys_fxstat
> +356 i386 xgetdents sys_xgetdents
> diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
> index 1308ee3..566aab1 100644
> --- a/arch/x86/syscalls/syscall_64.tbl
> +++ b/arch/x86/syscalls/syscall_64.tbl
> @@ -325,6 +325,7 @@
> 316 common renameat2 sys_renameat2
> 317 common xstat sys_xstat
> 318 common fxstat sys_fxstat
> +319 common xgetdents sys_xgetdents
>
> #
> # x32-specific system call numbers start at 512 to avoid cache impact
> diff --git a/fs/readdir.c b/fs/readdir.c
> index 33fd922..d676088 100644
> --- a/fs/readdir.c
> +++ b/fs/readdir.c
> @@ -224,6 +224,48 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
> return error;
> }
>
> +SYSCALL_DEFINE5(xgetdents, unsigned int, fd, unsigned, flags, unsigned int, mask,
> + void __user *, buf, unsigned int, count)
> +{
> + struct fd f;
> + struct inode *inode;
> + int error = -ENOTDIR;
> +
> + if (!count)
> + return -EINVAL;
> +
> + if (!access_ok(VERIFY_WRITE, buf, count))
> + return -EFAULT;
> +
> + f = fdget(fd);
> + if (!f.file)
> + return -EBADF;
> +
> + inode = f.file->f_path.dentry->d_inode;
> +
> + error = -ENOTSUPP;
> + if (!f.file->f_op || !f.file->f_op->xreaddir)
> + goto out;
> +
> + error = security_file_permission(f.file, MAY_READ);
> + if (error)
> + goto out;
> +
> + error = mutex_lock_killable(&inode->i_mutex);
> + if (error)
> + goto out;
> +
> + error = -ENOENT;
> + if (!IS_DEADDIR(inode)) {
> + error = f.file->f_op->xreaddir(f.file, flags, mask, buf, count);
> + file_accessed(f.file);
> + }
> + mutex_unlock(&inode->i_mutex);
> +out:
> + fdput(f);
> + return error;
> +}
> +
> struct getdents_callback64 {
> struct dir_context ctx;
> struct linux_dirent64 __user * current_dir;
> diff --git a/fs/stat.c b/fs/stat.c
> index 1fd0b3e..db45f8b 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -651,7 +651,7 @@ static int xstat_get_params(unsigned int mask, struct xstat __user *buffer,
> * Otherwise we copy the extended stats to userspace and return the amount of
> * data written into the buffer (or -EFAULT).
> */
> -static long xstat_set_result(struct kstat *stat, struct xstat __user *buffer)
> +long xstat_set_result(struct kstat *stat, struct xstat __user *buffer)
> {
> u32 mask = stat->result_mask, gran = stat->tv_granularity;
>
> @@ -701,6 +701,8 @@ static long xstat_set_result(struct kstat *stat, struct xstat __user *buffer)
> return 0;
> }
>
> +EXPORT_SYMBOL(xstat_set_result);
> +
> /*
> * System call to get extended stats by path
> */
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index b91f235..79c7d39 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1464,6 +1464,7 @@ struct file_operations {
> ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
> ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
> int (*iterate) (struct file *, struct dir_context *);
> + size_t (*xreaddir) (struct file *, unsigned int, unsigned int, void __user *, size_t);
> unsigned int (*poll) (struct file *, struct poll_table_struct *);
> long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
> long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
> diff --git a/include/linux/stat.h b/include/linux/stat.h
> index 552e047..75be415 100644
> --- a/include/linux/stat.h
> +++ b/include/linux/stat.h
> @@ -46,4 +46,6 @@ struct kstat {
> unsigned char volume_id[16]; /* volume identifier */
> };
>
> +long xstat_set_result(struct kstat *stat, struct xstat __user *buffer);
> +
> #endif
> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
> index 2907352..d7ea6c5 100644
> --- a/include/uapi/linux/stat.h
> +++ b/include/uapi/linux/stat.h
> @@ -90,6 +90,14 @@
> #define XSTAT_VOLUME_ID 0x00008000U /* want/got st_volume_id */
> #define XSTAT_ALL_STATS 0x0000ffffU /* all supported stats */
>
> +/* xattr request flags */
> +#define XSTAT_XATTR_USER 0x00010000U /* user.* xattrs */
> +#define XSTAT_XATTR_SYSTEM 0x00020000U /* system.* xattrs */
> +#define XSTAT_XATTR_SECURITY 0x00040000U /* security.* xattrs */
> +#define XSTAT_XATTR_POSIX_ACL 0x00080000U /* posix acl xattrs */
> +#define XSTAT_XATTR_ALL 0x00ff0000U /* all xattrs */
> +#define XSTAT_XATTR_VALUES 0x01000000U /* retrieve values along with keys */
> +
> /*
> * Extended stat structures
> */
> @@ -152,4 +160,29 @@ struct xstat {
> #define XSTAT_INFO_SYSTEM 0x00001000U /* File is marked system (DOS+) */
> #define XSTAT_INFO_ARCHIVE 0x00002000U /* File is marked archive (DOS+) */
>
> +struct xdirent_xattr {
> + size_t xa_value_len; /* length of value field */
> + char xa_name_val[1]; /* name/value pair, name is NULL terminated and
> + * value is xa_value_len in length */
> +};
> +
> +/*
> + * xb_blob: first contains NULL terminated name, followed by struct xdirent_xattr
> + * objects packed together.
> + */
> +struct xdirent_blob {
> + unsigned int xb_xattr_count;
> + char xb_blob[1]; /* contains variable length data like
> + * NULL-terminated name, xattrs etc */
> +};
> +
> +struct linux_xdirent {
> + unsigned long xd_ino;
> + char xd_type;
> + unsigned long xd_off;
> + struct xstat xd_stat;
> + unsigned long xd_reclen;
> + struct xdirent_blob xd_blob;
> +};
> +
> #endif /* _UAPI_LINUX_STAT_H */
> --
> 1.8.1.4
>
> --
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--
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface", http://blog.man7.org/
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