Also adds a void *opaque field to struct dir_context that can be
used by filesystems to temporarily store any context as this
struct gets passed around in the fs.
Signed-off-by: Abhi Das <adas@xxxxxxxxxx>
---
arch/x86/syscalls/syscall_32.tbl | 1 +
arch/x86/syscalls/syscall_64.tbl | 1 +
fs/readdir.c | 49 ++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 3 +++
4 files changed, 54 insertions(+)
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index d6b8679..3e0ef85 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -360,3 +360,4 @@
351 i386 sched_setattr sys_sched_setattr
352 i386 sched_getattr sys_sched_getattr
353 i386 renameat2 sys_renameat2
+354 i386 dirreadahead sys_dirreadahead
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index ec255a1..2ec0991 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -323,6 +323,7 @@
314 common sched_setattr sys_sched_setattr
315 common sched_getattr sys_sched_getattr
316 common renameat2 sys_renameat2
+317 common dirreadahead sys_dirreadahead
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/readdir.c b/fs/readdir.c
index 33fd922..d216db7 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -198,6 +198,7 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
struct linux_dirent __user * lastdirent;
struct getdents_callback buf = {
.ctx.actor = filldir,
+ .ctx.opaque = NULL,
.count = count,
.current_dir = dirent
};
@@ -278,6 +279,7 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
struct linux_dirent64 __user * lastdirent;
struct getdents_callback64 buf = {
.ctx.actor = filldir64,
+ .ctx.opaque = NULL,
.count = count,
.current_dir = dirent
};
@@ -304,3 +306,50 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
fdput(f);
return error;
}
+
+SYSCALL_DEFINE3(dirreadahead, unsigned int, fd,
+ loff_t __user *, offset, unsigned int, count)
+{
+ struct fd f;
+ struct inode *inode;
+ int error = -ENOTDIR;
+ loff_t off = 0;
+ struct dir_context ctx = {.actor = NULL, .opaque = NULL};
+
+ if (!count)
+ return -EINVAL;
+
+ 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->dir_readahead)
+ goto out;
+
+ error = security_file_permission(f.file, MAY_READ);
+ if (error)
+ goto out;
+
+ error = -EFAULT;
+ if (__get_user(ctx.pos, offset))
+ goto out;
+
+ error = mutex_lock_killable(&inode->i_mutex);
+ if (error)
+ goto out;
+
+ error = -ENOENT;
+ if (!IS_DEADDIR(inode)) {
+ error = f.file->f_op->dir_readahead(f.file, &ctx, count);
+ if (__put_user(ctx.pos, offset))
+ error = -EFAULT;
+ file_accessed(f.file);
+ }
+ mutex_unlock(&inode->i_mutex);
+out:
+ fdput(f);
+ return error;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 338e6f7..fae4a6e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1438,9 +1438,11 @@ int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
* to have different dirent layouts depending on the binary type.
*/
typedef int (*filldir_t)(void *, const char *, int, loff_t, u64, unsigned);
+
struct dir_context {
const filldir_t actor;
loff_t pos;
+ void *opaque;
};
struct block_device_operations;
@@ -1463,6 +1465,7 @@ 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 *);
+ int (*dir_readahead) (struct file *, struct dir_context *, unsigned int);
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);
--
1.8.1.4
--
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