ashmem: Support lseek(2) in ashmem driver

Signed-off-by: Bjorn Bringert <bringert@android.com>
[jstultz: tweaked commit subject]
CC: Brian Swetland <swetland@google.com>
CC: Colin Cross <ccross@android.com>
CC: Arve Hjønnevåg <arve@android.com>
CC: Dima Zavin <dima@android.com>
CC: Robert Love <rlove@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 38 insertions, 1 deletions

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 40c3dc867bf..777e2b257d4 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -178,7 +178,7 @@ static int ashmem_open(struct inode *inode, struct file *file)
         struct ashmem_area *asma;
         int ret;
 
-        ret = nonseekable_open(inode, file);
+        ret = generic_file_open(inode, file);
         if (unlikely(ret))
                 return ret;
 
@@ -230,6 +230,42 @@ static ssize_t ashmem_read(struct file *file, char __user *buf,
         }
 
         ret = asma->file->f_op->read(asma->file, buf, len, pos);
+        if (ret < 0) {
+                goto out;
+        }
+
+        /** Update backing file pos, since f_ops->read() doesn't */
+        asma->file->f_pos = *pos;
+
+out:
+        mutex_unlock(&ashmem_mutex);
+        return ret;
+}
+
+static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
+{
+        struct ashmem_area *asma = file->private_data;
+        int ret;
+
+        mutex_lock(&ashmem_mutex);
+
+        if (asma->size == 0) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (!asma->file) {
+                ret = -EBADF;
+                goto out;
+        }
+
+        ret = asma->file->f_op->llseek(asma->file, offset, origin);
+        if (ret < 0) {
+                goto out;
+        }
+
+        /** Copy f_pos from backing file, since f_ops->llseek() sets it */
+        file->f_pos = asma->file->f_pos;
 
 out:
         mutex_unlock(&ashmem_mutex);
@@ -648,6 +684,7 @@ static struct file_operations ashmem_fops = {
         .open = ashmem_open,
         .release = ashmem_release,
         .read = ashmem_read,
+        .llseek = ashmem_llseek,
         .mmap = ashmem_mmap,
         .unlocked_ioctl = ashmem_ioctl,
         .compat_ioctl = ashmem_ioctl,