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Subject[PATCH 03/14] Unionfs: implement splice_read/write methods directly
Date
Must implement splice_read/write directly, using VFS helpers, because we can
no longer rely on generic_file_splice_read/write: they need
address_space_operations implemented, which we no longer have.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
fs/unionfs/file.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++-
fs/unionfs/union.h | 1 +
2 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/fs/unionfs/file.c b/fs/unionfs/file.c
index 0c424f6..1fcaf8e 100644
--- a/fs/unionfs/file.c
+++ b/fs/unionfs/file.c
@@ -165,6 +165,61 @@ out:
return err;
}

+static ssize_t unionfs_splice_read(struct file *file, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ ssize_t err;
+ struct file *lower_file;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb, UNIONFS_SMUTEX_PARENT);
+ err = unionfs_file_revalidate(file, false);
+ if (unlikely(err))
+ goto out;
+
+ lower_file = unionfs_lower_file(file);
+ err = vfs_splice_to(lower_file, ppos, pipe, len, flags);
+ /* update our inode atime upon a successful lower splice-read */
+ if (err >= 0) {
+ fsstack_copy_attr_atime(file->f_path.dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+ unionfs_check_file(file);
+ }
+
+out:
+ unionfs_check_file(file);
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
+static ssize_t unionfs_splice_write(struct pipe_inode_info *pipe,
+ struct file *file, loff_t *ppos,
+ size_t len, unsigned int flags)
+{
+ ssize_t err = 0;
+ struct file *lower_file;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb, UNIONFS_SMUTEX_PARENT);
+ err = unionfs_file_revalidate(file, true);
+ if (unlikely(err))
+ goto out;
+
+ lower_file = unionfs_lower_file(file);
+ err = vfs_splice_from(pipe, lower_file, ppos, len, flags);
+ /* update our inode times+sizes upon a successful lower write */
+ if (err >= 0) {
+ fsstack_copy_inode_size(file->f_path.dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+ fsstack_copy_attr_times(file->f_path.dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+ unionfs_check_file(file);
+ }
+
+out:
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
struct file_operations unionfs_main_fops = {
.llseek = generic_file_llseek,
.read = do_sync_read,
@@ -179,6 +234,6 @@ struct file_operations unionfs_main_fops = {
.release = unionfs_file_release,
.fsync = unionfs_fsync,
.fasync = unionfs_fasync,
- .splice_read = generic_file_splice_read,
- .splice_write = generic_file_splice_write,
+ .splice_read = unionfs_splice_read,
+ .splice_write = unionfs_splice_write,
};
diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index 533806c..7b55e33 100644
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -46,6 +46,7 @@
#include <linux/poison.h>
#include <linux/mman.h>
#include <linux/backing-dev.h>
+#include <linux/splice.h>

#include <asm/system.h>

--
1.5.2.2


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