From: Gao Xiang Date: Tue, 24 Mar 2026 15:54:07 +0000 (+0800) Subject: erofs: fix .fadvise() for page cache sharing X-Git-Tag: v7.0-rc6~43^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f0407ed923b7eb363424033fc12fe253da139c4;p=thirdparty%2Flinux.git erofs: fix .fadvise() for page cache sharing Currently, .fadvise() doesn't work well if page cache sharing is on since shared inodes belong to a pseudo fs generated with init_pseudo(), and sb->s_bdi is the default one &noop_backing_dev_info. Then, generic_fadvise() will just behave as a no-op if sb->s_bdi is &noop_backing_dev_info, but as the bdev fs (the bdev fs changes inode_to_bdi() instead), it's actually NOT a pure memfs. Let's generate a real bdi for erofs_ishare_mnt instead. Fixes: d86d7817c042 ("erofs: implement .fadvise for page cache share") Reviewed-by: Hongbo Li Signed-off-by: Gao Xiang --- diff --git a/fs/erofs/ishare.c b/fs/erofs/ishare.c index 829d50d5c717..ec433bacc592 100644 --- a/fs/erofs/ishare.c +++ b/fs/erofs/ishare.c @@ -200,8 +200,19 @@ struct inode *erofs_real_inode(struct inode *inode, bool *need_iput) int __init erofs_init_ishare(void) { - erofs_ishare_mnt = kern_mount(&erofs_anon_fs_type); - return PTR_ERR_OR_ZERO(erofs_ishare_mnt); + struct vfsmount *mnt; + int ret; + + mnt = kern_mount(&erofs_anon_fs_type); + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + /* generic_fadvise() doesn't work if s_bdi == &noop_backing_dev_info */ + ret = super_setup_bdi(mnt->mnt_sb); + if (ret) + kern_unmount(mnt); + else + erofs_ishare_mnt = mnt; + return ret; } void erofs_exit_ishare(void)