On Mon, Dec 11 2017, Al Viro wrote: > On Mon, Dec 11, 2017 at 05:04:05PM +1100, NeilBrown wrote: >> @@ -385,7 +385,9 @@ int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, >> { >> const struct export_operations *nop = inode->i_sb->s_export_op; >> >> - if (nop && nop->encode_fh) >> + if (nop) >> + return FILEID_INVALID; >> + if (nop->encode_fh) >> return nop->encode_fh(inode, fid->raw, max_len, parent); > > This might as well have been > > if (nop) > return FILEID_INVALID; > BUG(); > > Have you ever tested that? I have now - except for testing against Amazon EFS. Only problem is the one you found - thanks. NeilBrown -----------8<------------>8---------------- From: NeilBrown Date: Mon, 11 Dec 2017 16:41:01 +1100 Subject: [PATCH] fs/notify: fdinfo can report unsupported file handles. If a filesystem does not set sb->s_export_op, then it does not support filehandles and export_fs_encode_fh() and exportfs_encode_inode_fh() should not be called. They will use export_encode_fh() is which is a default that uses inode number generation number, but in general they may not be stable. So change exportfs_encode_inode_fh() to return FILEID_INVALID if called on an unsupported Filesystem. Currently only notify/fdinfo can do that. Also remove the WARNing from fdinfo when exportfs_encode_inode_fh() returns FILEID_INVALID, as that is no an erroneous condition. Signed-off-by: NeilBrown --- fs/exportfs/expfs.c | 4 +++- fs/notify/fdinfo.c | 4 +--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c index 329a5d103846..2fff333b750c 100644 --- a/fs/exportfs/expfs.c +++ b/fs/exportfs/expfs.c @@ -385,7 +385,9 @@ int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, { const struct export_operations *nop = inode->i_sb->s_export_op; - if (nop && nop->encode_fh) + if (!nop) + return FILEID_INVALID; + if (nop->encode_fh) return nop->encode_fh(inode, fid->raw, max_len, parent); return export_encode_fh(inode, fid, max_len, parent); diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c index d478629c728b..d1135ed61229 100644 --- a/fs/notify/fdinfo.c +++ b/fs/notify/fdinfo.c @@ -50,10 +50,8 @@ static void show_mark_fhandle(struct seq_file *m, struct inode *inode) size = f.handle.handle_bytes >> 2; ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, 0); - if ((ret == FILEID_INVALID) || (ret < 0)) { - WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret); + if ((ret == FILEID_INVALID) || (ret < 0)) return; - } f.handle.handle_type = ret; f.handle.handle_bytes = size * sizeof(u32); -- 2.14.0.rc0.dirty