ecryptfs: Provide a splice-read wrapper

Provide a splice_read wrapper for ecryptfs to update the access time on the
lower file after the operation.  Splicing from a direct I/O fd will update
the access time when ->read_iter() is called.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Tyler Hicks <code@tyhicks.com>
cc: ecryptfs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20230522135018.2742245-18-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 268b74499c28c7c76f8e3230b66d86fec2394ee6..284395587be04cfd155d88f4a45945648894ba47 100644 (file)
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -44,6 +44,31 @@ static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
        return rc;
 }
 
+/*
+ * ecryptfs_splice_read_update_atime
+ *
+ * generic_file_splice_read updates the atime of upper layer inode.  But, it
+ * doesn't give us a chance to update the atime of the lower layer inode.  This
+ * function is a wrapper to generic_file_read.  It updates the atime of the
+ * lower level inode if generic_file_read returns without any errors. This is
+ * to be used only for file reads.  The function to be used for directory reads
+ * is ecryptfs_read.
+ */
+static ssize_t ecryptfs_splice_read_update_atime(struct file *in, loff_t *ppos,
+                                                struct pipe_inode_info *pipe,
+                                                size_t len, unsigned int flags)
+{
+       ssize_t rc;
+       const struct path *path;
+
+       rc = generic_file_splice_read(in, ppos, pipe, len, flags);
+       if (rc >= 0) {
+               path = ecryptfs_dentry_to_lower_path(in->f_path.dentry);
+               touch_atime(path);
+       }
+       return rc;
+}
+
 struct ecryptfs_getdents_callback {
        struct dir_context ctx;
        struct dir_context *caller;
@@ -414,5 +439,5 @@ const struct file_operations ecryptfs_main_fops = {
        .release = ecryptfs_release,
        .fsync = ecryptfs_fsync,
        .fasync = ecryptfs_fasync,
-       .splice_read = generic_file_splice_read,
+       .splice_read = ecryptfs_splice_read_update_atime,
 };