@@ -384,8 +384,56 @@ static int erofs_fscache_share_file_open(struct inode *inode, struct file *filp)
return 0;
}
+static ssize_t erofs_fscache_share_file_read_iter(struct kiocb *iocb,
+ struct iov_iter *to)
+{
+ struct file *filp = iocb->ki_filp;
+ struct inode *inode = file_inode(filp);
+ struct file *realfile = filp->private_data;
+ struct inode *realinode = file_inode(realfile);
+ struct erofs_fscache_share_file_info *finfo = realfile->private_data;
+ ssize_t already_read = 0;
+ int ret = 0;
+
+ /* no need taking (shared) inode lock since it's a ro filesystem */
+ if (!iov_iter_count(to))
+ return 0;
+
+ if (IS_DAX(inode) || iocb->ki_flags & IOCB_DIRECT)
+ return -EOPNOTSUPP;
+
+ do {
+ struct folio *folio;
+ size_t bytes, copied, offset, fsize;
+ pgoff_t index = (finfo->pa + iocb->ki_pos) >> PAGE_SHIFT;
+
+ folio = read_cache_folio(realinode->i_mapping, index, NULL, NULL);
+ if (IS_ERR(folio)) {
+ ret = PTR_ERR(folio);
+ break;
+ }
+
+ fsize = folio_size(folio);
+ offset = iocb->ki_pos & (fsize - 1);
+ bytes = min_t(size_t, inode->i_size - iocb->ki_pos, iov_iter_count(to));
+ bytes = min_t(size_t, bytes, fsize - offset);
+ copied = copy_folio_to_iter(folio, offset, bytes, to);
+ folio_put(folio);
+ iocb->ki_pos += copied;
+ already_read += copied;
+ if (copied < bytes) {
+ ret = -EFAULT;
+ break;
+ }
+ } while (iov_iter_count(to) && iocb->ki_pos < inode->i_size);
+
+ file_accessed(filp);
+ return already_read ? already_read : ret;
+}
+
const struct file_operations erofs_fscache_share_file_fops = {
.llseek = generic_file_llseek,
+ .read_iter = erofs_fscache_share_file_read_iter,
.open = erofs_fscache_share_file_open,
.release = erofs_fscache_share_file_release,
};
When page cache sharing enabled, page caches are managed in the address space of blobs rather than erofs inodes. All erofs inodes sharing one chunk will refer to and share the page cache in the blob's address space. Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com> --- fs/erofs/fscache.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+)