ext4: Provide a splice-read wrapper

Provide a splice_read wrapper for Ext4.  This does the inode shutdown check
before proceeding.  Splicing from DAX files and O_DIRECT fds is handled by
the caller.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Theodore Ts'o <tytso@mit.edu>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Andreas Dilger <adilger.kernel@dilger.ca>
cc: linux-ext4@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/20230522135018.2742245-19-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index d101b3b0c7dad8ade55a08328a09ec4e1a4f7496..9f8bbd9d131cfe54578d0565673ad4a838787f56 100644 (file)
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -147,6 +147,17 @@ static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        return generic_file_read_iter(iocb, to);
 }
 
+static ssize_t ext4_file_splice_read(struct file *in, loff_t *ppos,
+                                    struct pipe_inode_info *pipe,
+                                    size_t len, unsigned int flags)
+{
+       struct inode *inode = file_inode(in);
+
+       if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+               return -EIO;
+       return generic_file_splice_read(in, ppos, pipe, len, flags);
+}
+
 /*
  * Called when an inode is released. Note that this is different
  * from ext4_file_open: open gets called at every open, but release
@@ -957,7 +968,7 @@ const struct file_operations ext4_file_operations = {
        .release        = ext4_release_file,
        .fsync          = ext4_sync_file,
        .get_unmapped_area = thp_get_unmapped_area,
-       .splice_read    = generic_file_splice_read,
+       .splice_read    = ext4_file_splice_read,
        .splice_write   = iter_file_splice_write,
        .fallocate      = ext4_fallocate,
 };