erofs: implement .fadvise for page cache share

This patch implements the .fadvise interface for page cache share.
Similar to overlayfs, it drops those clean, unused pages through
vfs_fadvise().

Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/ishare.c b/fs/erofs/ishare.c
index ad53a57dbcbcd83e68f8871df2a7c4e749ef1095..ce980320a8b99605496b2853687145bf41644aeb 100644 (file)
--- a/fs/erofs/ishare.c
+++ b/fs/erofs/ishare.c
@@ -151,6 +151,12 @@ static int erofs_ishare_mmap(struct file *file, struct vm_area_struct *vma)
        return generic_file_readonly_mmap(file, vma);
 }
 
+static int erofs_ishare_fadvise(struct file *file, loff_t offset,
+                               loff_t len, int advice)
+{
+       return vfs_fadvise(file->private_data, offset, len, advice);
+}
+
 const struct file_operations erofs_ishare_fops = {
        .open           = erofs_ishare_file_open,
        .llseek         = generic_file_llseek,
@@ -159,6 +165,7 @@ const struct file_operations erofs_ishare_fops = {
        .release        = erofs_ishare_file_release,
        .get_unmapped_area = thp_get_unmapped_area,
        .splice_read    = filemap_splice_read,
+       .fadvise        = erofs_ishare_fadvise,
 };
 
 struct inode *erofs_real_inode(struct inode *inode, bool *need_iput)