aufs: remount 3/5, refresh the opened files

As a part of branch-management, aufs maintains all cached inodes,
dentries, and opened files in remounting.
This commits handles the opened files by counting the number of them,
generating an array of their pointers. I don't like such array
approach, but I don't have another idea.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/file.c

@@ -84,6 +84,250 @@ out:
 
 /* ---------------------------------------------------------------------- */
 
+static int au_file_refresh_by_inode(struct file *file, int *need_reopen)
+{
+	int err;
+	struct au_pin pin;
+	struct au_finfo *finfo;
+	struct dentry *parent;
+	struct inode *inode;
+	struct super_block *sb;
+	struct au_cp_generic cpg = {
+		.dentry	= file->f_path.dentry,
+		.bdst	= -1,
+		.bsrc	= -1,
+		.len	= -1,
+		.pin	= &pin,
+		.flags	= AuCpup_DTIME
+	};
+
+	FiMustWriteLock(file);
+
+	err = 0;
+	finfo = au_fi(file);
+	sb = cpg.dentry->d_sb;
+	inode = d_inode(cpg.dentry);
+	cpg.bdst = au_ibtop(inode);
+	if (cpg.bdst == finfo->fi_btop || IS_ROOT(cpg.dentry))
+		goto out;
+
+	parent = dget_parent(cpg.dentry);
+	if (au_test_ro(sb, cpg.bdst, inode)) {
+		di_read_lock_parent(parent, !AuLock_IR);
+		err = AuWbrCopyup(au_sbi(sb), cpg.dentry);
+		cpg.bdst = err;
+		di_read_unlock(parent, !AuLock_IR);
+		if (unlikely(err < 0))
+			goto out_parent;
+		err = 0;
+	}
+
+	di_read_lock_parent(parent, AuLock_IR);
+	if (!S_ISDIR(inode->i_mode)
+	    && au_opt_test(au_mntflags(sb), PLINK)
+	    && au_plink_test(inode)
+	    && !d_unhashed(cpg.dentry)
+	    && cpg.bdst < au_dbtop(cpg.dentry)) {
+		err = au_test_and_cpup_dirs(cpg.dentry, cpg.bdst);
+		if (unlikely(err))
+			goto out_unlock;
+
+		/* always superio. */
+		err = au_pin(&pin, cpg.dentry, cpg.bdst, AuOpt_UDBA_NONE,
+			     AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+		if (!err) {
+			err = au_sio_cpup_simple(&cpg);
+			au_unpin(&pin);
+		}
+	}
+
+out_unlock:
+	di_read_unlock(parent, AuLock_IR);
+out_parent:
+	dput(parent);
+out:
+	return err;
+}
+
+static void au_do_refresh_dir(struct file *file)
+{
+	aufs_bindex_t bindex, bbot, new_bindex, brid;
+	struct au_hfile *p, tmp, *q;
+	struct au_finfo *finfo;
+	struct super_block *sb;
+	struct au_fidir *fidir;
+
+	FiMustWriteLock(file);
+
+	sb = file->f_path.dentry->d_sb;
+	finfo = au_fi(file);
+	fidir = finfo->fi_hdir;
+	AuDebugOn(!fidir);
+	p = fidir->fd_hfile + finfo->fi_btop;
+	brid = p->hf_br->br_id;
+	bbot = fidir->fd_bbot;
+	for (bindex = finfo->fi_btop; bindex <= bbot; bindex++, p++) {
+		if (!p->hf_file)
+			continue;
+
+		new_bindex = au_br_index(sb, p->hf_br->br_id);
+		if (new_bindex == bindex)
+			continue;
+		if (new_bindex < 0) {
+			au_set_h_fptr(file, bindex, NULL);
+			continue;
+		}
+
+		/* swap two lower inode, and loop again */
+		q = fidir->fd_hfile + new_bindex;
+		tmp = *q;
+		*q = *p;
+		*p = tmp;
+		if (tmp.hf_file) {
+			bindex--;
+			p--;
+		}
+	}
+
+	p = fidir->fd_hfile;
+	if (!d_unlinked(file->f_path.dentry)) {
+		bbot = au_sbbot(sb);
+		for (finfo->fi_btop = 0; finfo->fi_btop <= bbot;
+		     finfo->fi_btop++, p++)
+			if (p->hf_file) {
+				if (file_inode(p->hf_file))
+					break;
+				au_hfput(p, /*execed*/0);
+			}
+	} else {
+		bbot = au_br_index(sb, brid);
+		for (finfo->fi_btop = 0; finfo->fi_btop < bbot;
+		     finfo->fi_btop++, p++)
+			if (p->hf_file)
+				au_hfput(p, /*execed*/0);
+		bbot = au_sbbot(sb);
+	}
+
+	p = fidir->fd_hfile + bbot;
+	for (fidir->fd_bbot = bbot; fidir->fd_bbot >= finfo->fi_btop;
+	     fidir->fd_bbot--, p--)
+		if (p->hf_file) {
+			if (file_inode(p->hf_file))
+				break;
+			au_hfput(p, /*execed*/0);
+		}
+	AuDebugOn(fidir->fd_bbot < finfo->fi_btop);
+}
+
+/*
+ * after branch manipulating, refresh the file.
+ */
+static int refresh_file(struct file *file, int (*reopen)(struct file *file))
+{
+	int err, need_reopen, nbr;
+	aufs_bindex_t bbot, bindex;
+	struct dentry *dentry;
+	struct super_block *sb;
+	struct au_finfo *finfo;
+	struct au_hfile *hfile;
+
+	dentry = file->f_path.dentry;
+	sb = dentry->d_sb;
+	nbr = au_sbbot(sb) + 1;
+	finfo = au_fi(file);
+	if (!finfo->fi_hdir) {
+		hfile = &finfo->fi_htop;
+		AuDebugOn(!hfile->hf_file);
+		bindex = au_br_index(sb, hfile->hf_br->br_id);
+		AuDebugOn(bindex < 0);
+		if (bindex != finfo->fi_btop)
+			au_set_fbtop(file, bindex);
+	} else {
+		err = au_fidir_realloc(finfo, nbr, /*may_shrink*/0);
+		if (unlikely(err))
+			goto out;
+		au_do_refresh_dir(file);
+	}
+
+	err = 0;
+	need_reopen = 1;
+	err = au_file_refresh_by_inode(file, &need_reopen);
+	if (finfo->fi_hdir)
+		/* harmless if err */
+		au_fidir_realloc(finfo, nbr, /*may_shrink*/1);
+	if (!err && need_reopen && !d_unlinked(dentry))
+		err = reopen(file);
+	if (!err) {
+		au_update_figen(file);
+		goto out; /* success */
+	}
+
+	/* error, close all lower files */
+	if (finfo->fi_hdir) {
+		bbot = au_fbbot_dir(file);
+		for (bindex = au_fbtop(file); bindex <= bbot; bindex++)
+			au_set_h_fptr(file, bindex, NULL);
+	}
+
+out:
+	return err;
+}
+
+/* common function to regular file and dir */
+int au_reval_and_lock_fdi(struct file *file, int (*reopen)(struct file *file),
+			  int wlock, unsigned int fi_lsc)
+{
+	int err;
+	unsigned int sigen, figen;
+	aufs_bindex_t btop;
+	unsigned char pseudo_link;
+	struct dentry *dentry;
+	struct inode *inode;
+
+	err = 0;
+	dentry = file->f_path.dentry;
+	inode = d_inode(dentry);
+	sigen = au_sigen(dentry->d_sb);
+	fi_write_lock_nested(file, fi_lsc);
+	figen = au_figen(file);
+	if (!fi_lsc)
+		di_write_lock_child(dentry);
+	else
+		di_write_lock_child2(dentry);
+	btop = au_dbtop(dentry);
+	pseudo_link = (btop != au_ibtop(inode));
+	if (sigen == figen && !pseudo_link && au_fbtop(file) == btop) {
+		if (!wlock) {
+			di_downgrade_lock(dentry, AuLock_IR);
+			fi_downgrade_lock(file);
+		}
+		goto out; /* success */
+	}
+
+	AuDbg("sigen %d, figen %d\n", sigen, figen);
+	if (au_digen_test(dentry, sigen)) {
+		err = au_reval_dpath(dentry, sigen);
+		AuDebugOn(!err && au_digen_test(dentry, sigen));
+	}
+
+	if (!err)
+		err = refresh_file(file, reopen);
+	if (!err) {
+		if (!wlock) {
+			di_downgrade_lock(dentry, AuLock_IR);
+			fi_downgrade_lock(file);
+		}
+	} else {
+		di_write_unlock(dentry);
+		fi_write_unlock(file);
+	}
+
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
 /* cf. aufs_nopage() */
 /* for madvise(2) */
 static int aufs_readpage(struct file *file __maybe_unused, struct page *page)

fs/aufs/file.h

@@ -55,6 +55,8 @@ extern const struct address_space_operations aufs_aop;
 unsigned int au_file_roflags(unsigned int flags);
 struct file *au_h_open(struct dentry *dentry, aufs_bindex_t bindex, int flags,
 		       struct file *file);
+int au_reval_and_lock_fdi(struct file *file, int (*reopen)(struct file *file),
+			  int wlock, unsigned int fi_lsc);
 
 /* finfo.c */
 void au_hfput(struct au_hfile *hf, int execed);
@@ -93,6 +95,45 @@ static inline struct au_finfo *au_fi(struct file *file)
 #define fi_write_unlock(f)	au_rw_write_unlock(&au_fi(f)->fi_rwsem)
 #define fi_downgrade_lock(f)	au_rw_dgrade_lock(&au_fi(f)->fi_rwsem)
 
+/* lock subclass for finfo */
+enum {
+	AuLsc_FI_1,
+	AuLsc_FI_2
+};
+
+static inline void fi_read_lock_nested(struct file *f, unsigned int lsc)
+{
+	au_rw_read_lock_nested(&au_fi(f)->fi_rwsem, lsc);
+}
+
+static inline void fi_write_lock_nested(struct file *f, unsigned int lsc)
+{
+	au_rw_write_lock_nested(&au_fi(f)->fi_rwsem, lsc);
+}
+
+/*
+ * fi_read_lock_1, fi_write_lock_1,
+ * fi_read_lock_2, fi_write_lock_2
+ */
+#define AuReadLockFunc(name) \
+static inline void fi_read_lock_##name(struct file *f) \
+{ fi_read_lock_nested(f, AuLsc_FI_##name); }
+
+#define AuWriteLockFunc(name) \
+static inline void fi_write_lock_##name(struct file *f) \
+{ fi_write_lock_nested(f, AuLsc_FI_##name); }
+
+#define AuRWLockFuncs(name) \
+	AuReadLockFunc(name) \
+	AuWriteLockFunc(name)
+
+AuRWLockFuncs(1);
+AuRWLockFuncs(2);
+
+#undef AuReadLockFunc
+#undef AuWriteLockFunc
+#undef AuRWLockFuncs
+
 #define FiMustNoWaiters(f)	AuRwMustNoWaiters(&au_fi(f)->fi_rwsem)
 #define FiMustAnyLock(f)	AuRwMustAnyLock(&au_fi(f)->fi_rwsem)
 #define FiMustWriteLock(f)	AuRwMustWriteLock(&au_fi(f)->fi_rwsem)