1 files changed, 427 insertions, 0 deletions
diff --git a/fs/aufs/fhsm.c b/fs/aufs/fhsm.c
new file mode 100644
index 000000000000..f86a4c24fb26
--- /dev/null
+++ b/fs/aufs/fhsm.c
@@ -0,0 +1,427 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2011-2019 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/*
+ * File-based Hierarchy Storage Management
+ */
+
+#include <linux/anon_inodes.h>
+#include <linux/poll.h>
+#include <linux/seq_file.h>
+#include <linux/statfs.h>
+#include "aufs.h"
+
+static aufs_bindex_t au_fhsm_bottom(struct super_block *sb)
+{
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+
+	SiMustAnyLock(sb);
+
+	sbinfo = au_sbi(sb);
+	fhsm = &sbinfo->si_fhsm;
+	AuDebugOn(!fhsm);
+	return fhsm->fhsm_bottom;
+}
+
+void au_fhsm_set_bottom(struct super_block *sb, aufs_bindex_t bindex)
+{
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+
+	SiMustWriteLock(sb);
+
+	sbinfo = au_sbi(sb);
+	fhsm = &sbinfo->si_fhsm;
+	AuDebugOn(!fhsm);
+	fhsm->fhsm_bottom = bindex;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_fhsm_test_jiffy(struct au_sbinfo *sbinfo, struct au_branch *br)
+{
+	struct au_br_fhsm *bf;
+
+	bf = br->br_fhsm;
+	MtxMustLock(&bf->bf_lock);
+
+	return !bf->bf_readable
+		|| time_after(jiffies,
+			      bf->bf_jiffy + sbinfo->si_fhsm.fhsm_expire);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void au_fhsm_notify(struct super_block *sb, int val)
+{
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+
+	SiMustAnyLock(sb);
+
+	sbinfo = au_sbi(sb);
+	fhsm = &sbinfo->si_fhsm;
+	if (au_fhsm_pid(fhsm)
+	    && atomic_read(&fhsm->fhsm_readable) != -1) {
+		atomic_set(&fhsm->fhsm_readable, val);
+		if (val)
+			wake_up(&fhsm->fhsm_wqh);
+	}
+}
+
+static int au_fhsm_stfs(struct super_block *sb, aufs_bindex_t bindex,
+			struct aufs_stfs *rstfs, int do_lock, int do_notify)
+{
+	int err;
+	struct au_branch *br;
+	struct au_br_fhsm *bf;
+
+	br = au_sbr(sb, bindex);
+	AuDebugOn(au_br_rdonly(br));
+	bf = br->br_fhsm;
+	AuDebugOn(!bf);
+
+	if (do_lock)
+		mutex_lock(&bf->bf_lock);
+	else
+		MtxMustLock(&bf->bf_lock);
+
+	/* sb->s_root for NFS is unreliable */
+	err = au_br_stfs(br, &bf->bf_stfs);
+	if (unlikely(err)) {
+		AuErr1("FHSM failed (%d), b%d, ignored.\n", bindex, err);
+		goto out;
+	}
+
+	bf->bf_jiffy = jiffies;
+	bf->bf_readable = 1;
+	if (do_notify)
+		au_fhsm_notify(sb, /*val*/1);
+	if (rstfs)
+		*rstfs = bf->bf_stfs;
+
+out:
+	if (do_lock)
+		mutex_unlock(&bf->bf_lock);
+	au_fhsm_notify(sb, /*val*/1);
+
+	return err;
+}
+
+void au_fhsm_wrote(struct super_block *sb, aufs_bindex_t bindex, int force)
+{
+	int err;
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+	struct au_branch *br;
+	struct au_br_fhsm *bf;
+
+	AuDbg("b%d, force %d\n", bindex, force);
+	SiMustAnyLock(sb);
+
+	sbinfo = au_sbi(sb);
+	fhsm = &sbinfo->si_fhsm;
+	if (!au_ftest_si(sbinfo, FHSM)
+	    || fhsm->fhsm_bottom == bindex)
+		return;
+
+	br = au_sbr(sb, bindex);
+	bf = br->br_fhsm;
+	AuDebugOn(!bf);
+	mutex_lock(&bf->bf_lock);
+	if (force
+	    || au_fhsm_pid(fhsm)
+	    || au_fhsm_test_jiffy(sbinfo, br))
+		err = au_fhsm_stfs(sb, bindex, /*rstfs*/NULL, /*do_lock*/0,
+				  /*do_notify*/1);
+	mutex_unlock(&bf->bf_lock);
+}
+
+void au_fhsm_wrote_all(struct super_block *sb, int force)
+{
+	aufs_bindex_t bindex, bbot;
+	struct au_branch *br;
+
+	/* exclude the bottom */
+	bbot = au_fhsm_bottom(sb);
+	for (bindex = 0; bindex < bbot; bindex++) {
+		br = au_sbr(sb, bindex);
+		if (au_br_fhsm(br->br_perm))
+			au_fhsm_wrote(sb, bindex, force);
+	}
+}
+
+/* ---------------------------------------------------------------------- */
+
+static __poll_t au_fhsm_poll(struct file *file, struct poll_table_struct *wait)
+{
+	__poll_t mask;
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+
+	mask = 0;
+	sbinfo = file->private_data;
+	fhsm = &sbinfo->si_fhsm;
+	poll_wait(file, &fhsm->fhsm_wqh, wait);
+	if (atomic_read(&fhsm->fhsm_readable))
+		mask = EPOLLIN /* | EPOLLRDNORM */;
+
+	if (!mask)
+		AuDbg("mask 0x%x\n", mask);
+	return mask;
+}
+
+static int au_fhsm_do_read_one(struct aufs_stbr __user *stbr,
+			      struct aufs_stfs *stfs, __s16 brid)
+{
+	int err;
+
+	err = copy_to_user(&stbr->stfs, stfs, sizeof(*stfs));
+	if (!err)
+		err = __put_user(brid, &stbr->brid);
+	if (unlikely(err))
+		err = -EFAULT;
+
+	return err;
+}
+
+static ssize_t au_fhsm_do_read(struct super_block *sb,
+			       struct aufs_stbr __user *stbr, size_t count)
+{
+	ssize_t err;
+	int nstbr;
+	aufs_bindex_t bindex, bbot;
+	struct au_branch *br;
+	struct au_br_fhsm *bf;
+
+	/* except the bottom branch */
+	err = 0;
+	nstbr = 0;
+	bbot = au_fhsm_bottom(sb);
+	for (bindex = 0; !err && bindex < bbot; bindex++) {
+		br = au_sbr(sb, bindex);
+		if (!au_br_fhsm(br->br_perm))
+			continue;
+
+		bf = br->br_fhsm;
+		mutex_lock(&bf->bf_lock);
+		if (bf->bf_readable) {
+			err = -EFAULT;
+			if (count >= sizeof(*stbr))
+				err = au_fhsm_do_read_one(stbr++, &bf->bf_stfs,
+							  br->br_id);
+			if (!err) {
+				bf->bf_readable = 0;
+				count -= sizeof(*stbr);
+				nstbr++;
+			}
+		}
+		mutex_unlock(&bf->bf_lock);
+	}
+	if (!err)
+		err = sizeof(*stbr) * nstbr;
+
+	return err;
+}
+
+static ssize_t au_fhsm_read(struct file *file, char __user *buf, size_t count,
+			   loff_t *pos)
+{
+	ssize_t err;
+	int readable;
+	aufs_bindex_t nfhsm, bindex, bbot;
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+	struct au_branch *br;
+	struct super_block *sb;
+
+	err = 0;
+	sbinfo = file->private_data;
+	fhsm = &sbinfo->si_fhsm;
+need_data:
+	spin_lock_irq(&fhsm->fhsm_wqh.lock);
+	if (!atomic_read(&fhsm->fhsm_readable)) {
+		if (vfsub_file_flags(file) & O_NONBLOCK)
+			err = -EAGAIN;
+		else
+			err = wait_event_interruptible_locked_irq
+				(fhsm->fhsm_wqh,
+				 atomic_read(&fhsm->fhsm_readable));
+	}
+	spin_unlock_irq(&fhsm->fhsm_wqh.lock);
+	if (unlikely(err))
+		goto out;
+
+	/* sb may already be dead */
+	au_rw_read_lock(&sbinfo->si_rwsem);
+	readable = atomic_read(&fhsm->fhsm_readable);
+	if (readable > 0) {
+		sb = sbinfo->si_sb;
+		AuDebugOn(!sb);
+		/* exclude the bottom branch */
+		nfhsm = 0;
+		bbot = au_fhsm_bottom(sb);
+		for (bindex = 0; bindex < bbot; bindex++) {
+			br = au_sbr(sb, bindex);
+			if (au_br_fhsm(br->br_perm))
+				nfhsm++;
+		}
+		err = -EMSGSIZE;
+		if (nfhsm * sizeof(struct aufs_stbr) <= count) {
+			atomic_set(&fhsm->fhsm_readable, 0);
+			err = au_fhsm_do_read(sbinfo->si_sb, (void __user *)buf,
+					     count);
+		}
+	}
+	au_rw_read_unlock(&sbinfo->si_rwsem);
+	if (!readable)
+		goto need_data;
+
+out:
+	return err;
+}
+
+static int au_fhsm_release(struct inode *inode, struct file *file)
+{
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+
+	/* sb may already be dead */
+	sbinfo = file->private_data;
+	fhsm = &sbinfo->si_fhsm;
+	spin_lock(&fhsm->fhsm_spin);
+	fhsm->fhsm_pid = 0;
+	spin_unlock(&fhsm->fhsm_spin);
+	kobject_put(&sbinfo->si_kobj);
+
+	return 0;
+}
+
+static const struct file_operations au_fhsm_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= noop_llseek,
+	.read		= au_fhsm_read,
+	.poll		= au_fhsm_poll,
+	.release	= au_fhsm_release
+};
+
+int au_fhsm_fd(struct super_block *sb, int oflags)
+{
+	int err, fd;
+	struct au_sbinfo *sbinfo;
+	struct au_fhsm *fhsm;
+
+	err = -EPERM;
+	if (unlikely(!capable(CAP_SYS_ADMIN)))
+		goto out;
+
+	err = -EINVAL;
+	if (unlikely(oflags & ~(O_CLOEXEC | O_NONBLOCK)))
+		goto out;
+
+	err = 0;
+	sbinfo = au_sbi(sb);
+	fhsm = &sbinfo->si_fhsm;
+	spin_lock(&fhsm->fhsm_spin);
+	if (!fhsm->fhsm_pid)
+		fhsm->fhsm_pid = current->pid;
+	else
+		err = -EBUSY;
+	spin_unlock(&fhsm->fhsm_spin);
+	if (unlikely(err))
+		goto out;
+
+	oflags |= O_RDONLY;
+	/* oflags |= FMODE_NONOTIFY; */
+	fd = anon_inode_getfd("[aufs_fhsm]", &au_fhsm_fops, sbinfo, oflags);
+	err = fd;
+	if (unlikely(fd < 0))
+		goto out_pid;
+
+	/* succeed regardless 'fhsm' status */
+	kobject_get(&sbinfo->si_kobj);
+	si_noflush_read_lock(sb);
+	if (au_ftest_si(sbinfo, FHSM))
+		au_fhsm_wrote_all(sb, /*force*/0);
+	si_read_unlock(sb);
+	goto out; /* success */
+
+out_pid:
+	spin_lock(&fhsm->fhsm_spin);
+	fhsm->fhsm_pid = 0;
+	spin_unlock(&fhsm->fhsm_spin);
+out:
+	AuTraceErr(err);
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_fhsm_br_alloc(struct au_branch *br)
+{
+	int err;
+
+	err = 0;
+	br->br_fhsm = kmalloc(sizeof(*br->br_fhsm), GFP_NOFS);
+	if (br->br_fhsm)
+		au_br_fhsm_init(br->br_fhsm);
+	else
+		err = -ENOMEM;
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void au_fhsm_fin(struct super_block *sb)
+{
+	au_fhsm_notify(sb, /*val*/-1);
+}
+
+void au_fhsm_init(struct au_sbinfo *sbinfo)
+{
+	struct au_fhsm *fhsm;
+
+	fhsm = &sbinfo->si_fhsm;
+	spin_lock_init(&fhsm->fhsm_spin);
+	init_waitqueue_head(&fhsm->fhsm_wqh);
+	atomic_set(&fhsm->fhsm_readable, 0);
+	fhsm->fhsm_expire
+		= msecs_to_jiffies(AUFS_FHSM_CACHE_DEF_SEC * MSEC_PER_SEC);
+	fhsm->fhsm_bottom = -1;
+}
+
+void au_fhsm_set(struct au_sbinfo *sbinfo, unsigned int sec)
+{
+	sbinfo->si_fhsm.fhsm_expire
+		= msecs_to_jiffies(sec * MSEC_PER_SEC);
+}
+
+void au_fhsm_show(struct seq_file *seq, struct au_sbinfo *sbinfo)
+{
+	unsigned int u;
+
+	if (!au_ftest_si(sbinfo, FHSM))
+		return;
+
+	u = jiffies_to_msecs(sbinfo->si_fhsm.fhsm_expire) / MSEC_PER_SEC;
+	if (u != AUFS_FHSM_CACHE_DEF_SEC)
+		seq_printf(seq, ",fhsm_sec=%u", u);
+}