[Aufs 06/25] aufs xino

[J. R. Okajima]

initial commit
external inode number translation table and bitmap

Signed-off-by: J. R. Okajima <hooanon05@xxxxxxxxxxx>
---
 fs/aufs/xino.c | 1181 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 1181 insertions(+), 0 deletions(-)
 create mode 100644 fs/aufs/xino.c

diff --git a/fs/aufs/xino.c b/fs/aufs/xino.c
new file mode 100644
index 0000000..bc19b86
--- /dev/null
+++ b/fs/aufs/xino.c
@@ -0,0 +1,1181 @@
+/*
+ * Copyright (C) 2005-2009 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.
+ */
+
+/*
+ * external inode number translation table and bitmap
+ */
+
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include "aufs.h"
+
+ssize_t xino_fread(au_readf_t func, struct file *file, void *buf, size_t size,
+		   loff_t *pos)
+{
+	ssize_t err;
+	mm_segment_t oldfs;
+
+	oldfs = get_fs();
+	set_fs(KERNEL_DS);
+	do {
+		/* todo: signal_pending? */
+		err = func(file, (char __user *)buf, size, pos);
+	} while (err == -EAGAIN || err == -EINTR);
+	set_fs(oldfs);
+
+#if 0 /* reserved for future use */
+	if (err > 0)
+		fsnotify_access(file->f_dentry);
+#endif
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static ssize_t do_xino_fwrite(au_writef_t func, struct file *file, void *buf,
+			      size_t size, loff_t *pos)
+{
+	ssize_t err;
+	mm_segment_t oldfs;
+
+	oldfs = get_fs();
+	set_fs(KERNEL_DS);
+	lockdep_off();
+	do {
+		/* todo: signal_pending? */
+		err = func(file, (const char __user *)buf, size, pos);
+	} while (err == -EAGAIN || err == -EINTR);
+	lockdep_on();
+	set_fs(oldfs);
+
+#if 0 /* reserved for future use */
+	if (err > 0)
+		fsnotify_modify(file->f_dentry);
+#endif
+
+	return err;
+}
+
+struct do_xino_fwrite_args {
+	ssize_t *errp;
+	au_writef_t func;
+	struct file *file;
+	void *buf;
+	size_t size;
+	loff_t *pos;
+};
+
+static void call_do_xino_fwrite(void *args)
+{
+	struct do_xino_fwrite_args *a = args;
+	*a->errp = do_xino_fwrite(a->func, a->file, a->buf, a->size, a->pos);
+}
+
+ssize_t xino_fwrite(au_writef_t func, struct file *file, void *buf, size_t size,
+		    loff_t *pos)
+{
+	ssize_t err;
+
+	/* todo: signal block and no wkq? */
+	/* todo: new credential scheme */
+	/*
+	 * it breaks RLIMIT_FSIZE and normal user's limit,
+	 * users should care about quota and real 'filesystem full.'
+	 */
+	if (!au_test_wkq(current)) {
+		int wkq_err;
+		struct do_xino_fwrite_args args = {
+			.errp	= &err,
+			.func	= func,
+			.file	= file,
+			.buf	= buf,
+			.size	= size,
+			.pos	= pos
+		};
+
+		wkq_err = au_wkq_wait(call_do_xino_fwrite, &args);
+		if (unlikely(wkq_err))
+			err = wkq_err;
+	} else
+		err = do_xino_fwrite(func, file, buf, size, pos);
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * create a new xinofile at the same place/path as @base_file.
+ */
+static struct file *au_xino_create2(struct file *base_file,
+				    struct file *copy_src)
+{
+	struct file *file;
+	struct dentry *base, *dentry, *parent;
+	struct inode *dir;
+	struct qstr *name;
+	int err;
+
+	base = base_file->f_dentry;
+	parent = base->d_parent; /* dir inode is locked */
+	dir = parent->d_inode;
+	IMustLock(dir);
+
+	file = ERR_PTR(-EINVAL);
+	name = &base->d_name;
+	dentry = vfsub_lookup_one_len(name->name, parent, name->len);
+	if (IS_ERR(dentry)) {
+		file = (void *)dentry;
+		AuErr("%.*s lookup err %ld\n", AuLNPair(name), PTR_ERR(dentry));
+		goto out;
+	}
+
+	/* no need to mnt_want_write() since we call dentry_open() later */
+	err = vfs_create(dir, dentry, S_IRUGO | S_IWUGO, NULL);
+	if (unlikely(err)) {
+		file = ERR_PTR(err);
+		AuErr("%.*s create err %d\n", AuLNPair(name), err);
+		goto out_dput;
+	}
+
+	file = dentry_open(dget(dentry), mntget(base_file->f_vfsmnt),
+			   O_RDWR | O_CREAT | O_EXCL | O_LARGEFILE,
+			   current_cred());
+	if (IS_ERR(file)) {
+		AuErr("%.*s open err %ld\n", AuLNPair(name), PTR_ERR(file));
+		goto out_dput;
+	}
+
+	err = vfsub_unlink(dir, &file->f_path, /*force*/0);
+	if (unlikely(err)) {
+		AuErr("%.*s unlink err %d\n", AuLNPair(name), err);
+		goto out_fput;
+	}
+
+	if (copy_src) {
+		/* no one can touch copy_src xino */
+		err = au_copy_file(file, copy_src,
+				   i_size_read(copy_src->f_dentry->d_inode));
+		if (unlikely(err)) {
+			AuErr("%.*s copy err %d\n", AuLNPair(name), err);
+			goto out_fput;
+		}
+	}
+	goto out_dput; /* success */
+
+ out_fput:
+	fput(file);
+	file = ERR_PTR(err);
+ out_dput:
+	dput(dentry);
+ out:
+	return file;
+}
+
+struct au_xino_lock_dir {
+	struct au_hinode *hdir;
+	struct dentry *parent;
+	struct mutex *mtx;
+};
+
+static void au_xino_lock_dir(struct super_block *sb, struct file *xino,
+			     struct au_xino_lock_dir *ldir)
+{
+	aufs_bindex_t brid, bindex;
+
+	ldir->hdir = NULL;
+	bindex = -1;
+	brid = au_xino_brid(sb);
+	if (brid >= 0)
+		bindex = au_br_index(sb, brid);
+	if (bindex >= 0) {
+		ldir->hdir = au_hi(sb->s_root->d_inode, bindex);
+		au_hin_imtx_lock_nested(ldir->hdir, AuLsc_I_PARENT);
+	} else {
+		ldir->parent = dget_parent(xino->f_dentry);
+		ldir->mtx = &ldir->parent->d_inode->i_mutex;
+		mutex_lock_nested(ldir->mtx, AuLsc_I_PARENT);
+	}
+}
+
+static void au_xino_unlock_dir(struct au_xino_lock_dir *ldir)
+{
+	if (ldir->hdir)
+		au_hin_imtx_unlock(ldir->hdir);
+	else {
+		mutex_unlock(ldir->mtx);
+		dput(ldir->parent);
+	}
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* trucate xino files asynchronously */
+
+int au_xino_trunc(struct super_block *sb, aufs_bindex_t bindex)
+{
+	int err;
+	aufs_bindex_t bi, bend;
+	struct au_branch *br;
+	struct file *new_xino, *file;
+	struct super_block *h_sb;
+	struct au_xino_lock_dir ldir;
+
+	err = -EINVAL;
+	bend = au_sbend(sb);
+	if (unlikely(bindex < 0 || bend < bindex))
+		goto out;
+	br = au_sbr(sb, bindex);
+	file = br->br_xino.xi_file;
+	if (!file)
+		goto out;
+
+	au_xino_lock_dir(sb, file, &ldir);
+	/* mnt_want_write() is unnecessary here */
+	new_xino = au_xino_create2(file, file);
+	au_xino_unlock_dir(&ldir);
+	err = PTR_ERR(new_xino);
+	if (IS_ERR(new_xino))
+		goto out;
+	err = 0;
+	fput(file);
+	br->br_xino.xi_file = new_xino;
+
+	h_sb = br->br_mnt->mnt_sb;
+	for (bi = 0; bi <= bend; bi++) {
+		if (unlikely(bi == bindex))
+			continue;
+		br = au_sbr(sb, bi);
+		if (br->br_mnt->mnt_sb != h_sb)
+			continue;
+
+		fput(br->br_xino.xi_file);
+		br->br_xino.xi_file = new_xino;
+		get_file(new_xino);
+	}
+
+ out:
+	return err;
+}
+
+struct xino_do_trunc_args {
+	struct super_block *sb;
+	struct au_branch *br;
+};
+
+static void xino_do_trunc(void *_args)
+{
+	struct xino_do_trunc_args *args = _args;
+	struct super_block *sb;
+	struct au_branch *br;
+	struct inode *dir;
+	int err;
+	aufs_bindex_t bindex;
+
+	err = 0;
+	sb = args->sb;
+	dir = sb->s_root->d_inode;
+	br = args->br;
+
+	si_noflush_write_lock(sb);
+	ii_read_lock_parent(dir);
+	bindex = au_br_index(sb, br->br_id);
+	err = au_xino_trunc(sb, bindex);
+	if (unlikely(err))
+		goto out;
+
+	if (br->br_xino.xi_file->f_dentry->d_inode->i_blocks
+	    >= br->br_xino_upper)
+		br->br_xino_upper += AUFS_XINO_TRUNC_STEP;
+
+ out:
+	ii_read_unlock(dir);
+	if (unlikely(err))
+		AuWarn("err b%d, (%d)\n", bindex, err);
+	atomic_dec(&br->br_xino_running);
+	atomic_dec(&br->br_count);
+	au_nwt_done(&au_sbi(sb)->si_nowait);
+	si_write_unlock(sb);
+	kfree(args);
+}
+
+static void xino_try_trunc(struct super_block *sb, struct au_branch *br)
+{
+	struct xino_do_trunc_args *args;
+	int wkq_err;
+
+	if (br->br_xino.xi_file->f_dentry->d_inode->i_blocks
+	    < br->br_xino_upper)
+		return;
+
+	if (atomic_inc_return(&br->br_xino_running) > 1)
+		goto out;
+
+	/* lock and kfree() will be called in trunc_xino() */
+	args = kmalloc(sizeof(*args), GFP_NOFS);
+	if (unlikely(!args)) {
+		AuErr1("no memory\n");
+		goto out_args;
+	}
+
+	atomic_inc(&br->br_count);
+	args->sb = sb;
+	args->br = br;
+	wkq_err = au_wkq_nowait(xino_do_trunc, args, sb);
+	if (!wkq_err)
+		return; /* success */
+
+	AuErr("wkq %d\n", wkq_err);
+	atomic_dec(&br->br_count);
+
+ out_args:
+	kfree(args);
+ out:
+	atomic_dec(&br->br_xino_running);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static const loff_t au_loff_max = LLONG_MAX;
+
+static int au_xino_do_write(au_writef_t write, struct file *file,
+			    ino_t h_ino, ino_t ino)
+{
+	loff_t pos;
+	ssize_t sz;
+
+	pos = h_ino;
+	if (unlikely(au_loff_max / sizeof(ino) - 1 < pos)) {
+		AuIOErr1("too large hi%lu\n", (unsigned long)h_ino);
+		return -EFBIG;
+	}
+	pos *= sizeof(ino);
+	sz = xino_fwrite(write, file, &ino, sizeof(ino), &pos);
+	if (sz == sizeof(ino))
+		return 0; /* success */
+
+	AuIOErr("write failed (%zd)\n", sz);
+	return -EIO;
+}
+
+/*
+ * write @ino to the xinofile for the specified branch{@sb, @bindex}
+ * at the position of @h_ino.
+ * even if @ino is zero, it is written to the xinofile and means no entry.
+ * if the size of the xino file on a specific filesystem exceeds the watermark,
+ * try truncating it.
+ */
+int au_xino_write(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+		  ino_t ino)
+{
+	int err;
+	unsigned int mnt_flags;
+	struct au_branch *br;
+
+	BUILD_BUG_ON(sizeof(long long) != sizeof(au_loff_max)
+		     || ((loff_t)-1) > 0);
+
+	mnt_flags = au_mntflags(sb);
+	if (!au_opt_test(mnt_flags, XINO))
+		return 0;
+
+	br = au_sbr(sb, bindex);
+	err = au_xino_do_write(au_sbi(sb)->si_xwrite, br->br_xino.xi_file,
+			       h_ino, ino);
+	if (!err) {
+		if (au_opt_test(mnt_flags, TRUNC_XINO)
+		    && au_test_fs_trunc_xino(br->br_mnt->mnt_sb))
+			xino_try_trunc(sb, br);
+		return 0; /* success */
+	}
+
+	AuIOErr("write failed (%d)\n", err);
+	return -EIO;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* aufs inode number bitmap */
+
+static const int page_bits = (int)PAGE_SIZE * BITS_PER_BYTE;
+static ino_t xib_calc_ino(unsigned long pindex, int bit)
+{
+	ino_t ino;
+
+	AuDebugOn(bit < 0 || page_bits <= bit);
+	ino = AUFS_FIRST_INO + pindex * page_bits + bit;
+	return ino;
+}
+
+static void xib_calc_bit(ino_t ino, unsigned long *pindex, int *bit)
+{
+	AuDebugOn(ino < AUFS_FIRST_INO);
+	ino -= AUFS_FIRST_INO;
+	*pindex = ino / page_bits;
+	*bit = ino % page_bits;
+}
+
+static int xib_pindex(struct super_block *sb, unsigned long pindex)
+{
+	int err;
+	loff_t pos;
+	ssize_t sz;
+	struct au_sbinfo *sbinfo;
+	struct file *xib;
+	unsigned long *p;
+
+	sbinfo = au_sbi(sb);
+	MtxMustLock(&sbinfo->si_xib_mtx);
+	AuDebugOn(pindex > ULONG_MAX / PAGE_SIZE
+		  || !au_opt_test(sbinfo->si_mntflags, XINO));
+
+	if (pindex == sbinfo->si_xib_last_pindex)
+		return 0;
+
+	xib = sbinfo->si_xib;
+	p = sbinfo->si_xib_buf;
+	pos = sbinfo->si_xib_last_pindex;
+	pos *= PAGE_SIZE;
+	sz = xino_fwrite(sbinfo->si_xwrite, xib, p, PAGE_SIZE, &pos);
+	if (unlikely(sz != PAGE_SIZE))
+		goto out;
+
+	pos = pindex;
+	pos *= PAGE_SIZE;
+	if (i_size_read(xib->f_dentry->d_inode) >= pos + PAGE_SIZE)
+		sz = xino_fread(sbinfo->si_xread, xib, p, PAGE_SIZE, &pos);
+	else {
+		memset(p, 0, PAGE_SIZE);
+		sz = xino_fwrite(sbinfo->si_xwrite, xib, p, PAGE_SIZE, &pos);
+	}
+	if (sz == PAGE_SIZE) {
+		sbinfo->si_xib_last_pindex = pindex;
+		return 0; /* success */
+	}
+
+ out:
+	AuIOErr1("write failed (%zd)\n", sz);
+	err = sz;
+	if (sz >= 0)
+		err = -EIO;
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_xino_write0(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+		   ino_t ino)
+{
+	int err, bit;
+	unsigned long pindex;
+	struct au_sbinfo *sbinfo;
+
+	if (!au_opt_test(au_mntflags(sb), XINO))
+		return 0;
+
+	err = 0;
+	if (ino) {
+		sbinfo = au_sbi(sb);
+		xib_calc_bit(ino, &pindex, &bit);
+		AuDebugOn(page_bits <= bit);
+		mutex_lock(&sbinfo->si_xib_mtx);
+		err = xib_pindex(sb, pindex);
+		if (!err) {
+			clear_bit(bit, sbinfo->si_xib_buf);
+			sbinfo->si_xib_next_bit = bit;
+		}
+		mutex_unlock(&sbinfo->si_xib_mtx);
+	}
+
+	if (!err)
+		err = au_xino_write(sb, bindex, h_ino, 0);
+	return err;
+}
+
+/* get an unused inode number from bitmap */
+ino_t au_xino_new_ino(struct super_block *sb)
+{
+	ino_t ino;
+	unsigned long *p, pindex, ul, pend;
+	struct au_sbinfo *sbinfo;
+	struct file *file;
+	int free_bit, err;
+
+	if (!au_opt_test(au_mntflags(sb), XINO))
+		return iunique(sb, AUFS_FIRST_INO);
+
+	sbinfo = au_sbi(sb);
+	mutex_lock(&sbinfo->si_xib_mtx);
+	p = sbinfo->si_xib_buf;
+	free_bit = sbinfo->si_xib_next_bit;
+	if (free_bit < page_bits && !test_bit(free_bit, p))
+		goto out; /* success */
+	free_bit = find_first_zero_bit(p, page_bits);
+	if (free_bit < page_bits)
+		goto out; /* success */
+
+	pindex = sbinfo->si_xib_last_pindex;
+	for (ul = pindex - 1; ul < ULONG_MAX; ul--) {
+		err = xib_pindex(sb, ul);
+		if (unlikely(err))
+			goto out_err;
+		free_bit = find_first_zero_bit(p, page_bits);
+		if (free_bit < page_bits)
+			goto out; /* success */
+	}
+
+	file = sbinfo->si_xib;
+	pend = i_size_read(file->f_dentry->d_inode) / PAGE_SIZE;
+	for (ul = pindex + 1; ul <= pend; ul++) {
+		err = xib_pindex(sb, ul);
+		if (unlikely(err))
+			goto out_err;
+		free_bit = find_first_zero_bit(p, page_bits);
+		if (free_bit < page_bits)
+			goto out; /* success */
+	}
+	BUG();
+
+ out:
+	set_bit(free_bit, p);
+	sbinfo->si_xib_next_bit++;
+	pindex = sbinfo->si_xib_last_pindex;
+	mutex_unlock(&sbinfo->si_xib_mtx);
+	ino = xib_calc_ino(pindex, free_bit);
+	AuDbg("i%lu\n", (unsigned long)ino);
+	return ino;
+ out_err:
+	mutex_unlock(&sbinfo->si_xib_mtx);
+	AuDbg("i0\n");
+	return 0;
+}
+
+/*
+ * read @ino from xinofile for the specified branch{@sb, @bindex}
+ * at the position of @h_ino.
+ * if @ino does not exist and @do_new is true, get new one.
+ */
+int au_xino_read(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
+		 ino_t *ino)
+{
+	int err;
+	ssize_t sz;
+	loff_t pos;
+	struct file *file;
+	struct au_sbinfo *sbinfo;
+
+	*ino = 0;
+	if (!au_opt_test(au_mntflags(sb), XINO))
+		return 0; /* no xino */
+
+	err = 0;
+	sbinfo = au_sbi(sb);
+	pos = h_ino;
+	if (unlikely(au_loff_max / sizeof(*ino) - 1 < pos)) {
+		AuIOErr1("too large hi%lu\n", (unsigned long)h_ino);
+		return -EFBIG;
+	}
+	pos *= sizeof(*ino);
+
+	file = au_sbr(sb, bindex)->br_xino.xi_file;
+	if (i_size_read(file->f_dentry->d_inode) < pos + sizeof(*ino))
+		return 0; /* no ino */
+
+	sz = xino_fread(sbinfo->si_xread, file, ino, sizeof(*ino), &pos);
+	if (sz == sizeof(*ino))
+		return 0; /* success */
+
+	err = sz;
+	if (unlikely(sz >= 0)) {
+		err = -EIO;
+		AuIOErr("xino read error (%zd)\n", sz);
+	}
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* create and set a new xino file */
+
+struct file *au_xino_create(struct super_block *sb, char *fname, int silent)
+{
+	struct file *file;
+	struct dentry *h_parent, *d;
+	struct inode *h_dir;
+	int err;
+
+	/*
+	 * at mount-time, and the xino file is the default path,
+	 * hinotify is disabled so we have no inotify events to ignore.
+	 * when a user specified the xino, we cannot get au_hdir to be ignored.
+	 */
+	file = vfsub_filp_open(fname, O_RDWR | O_CREAT | O_EXCL | O_LARGEFILE,
+			       S_IRUGO | S_IWUGO);
+	if (IS_ERR(file)) {
+		if (!silent)
+			AuErr("open %s(%ld)\n", fname, PTR_ERR(file));
+		return file;
+	}
+
+	/* keep file count */
+	h_parent = dget_parent(file->f_dentry);
+	h_dir = h_parent->d_inode;
+	mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_PARENT);
+	/* mnt_want_write() is unnecessary here */
+	err = vfsub_unlink(h_dir, &file->f_path, /*force*/0);
+	mutex_unlock(&h_dir->i_mutex);
+	dput(h_parent);
+	if (unlikely(err)) {
+		if (!silent)
+			AuErr("unlink %s(%d)\n", fname, err);
+		goto out;
+	}
+
+	err = -EINVAL;
+	d = file->f_dentry;
+	if (unlikely(sb == d->d_sb)) {
+		if (!silent)
+			AuErr("%s must be outside\n", fname);
+		goto out;
+	}
+	if (unlikely(au_test_fs_bad_xino(d->d_sb))) {
+		if (!silent)
+			AuErr("xino doesn't support %s(%s)\n",
+			      fname, au_sbtype(d->d_sb));
+		goto out;
+	}
+	return file; /* success */
+
+ out:
+	fput(file);
+	file = ERR_PTR(err);
+	return file;
+}
+
+/*
+ * find another branch who is on the same filesystem of the specified
+ * branch{@btgt}. search until @bend.
+ */
+static int is_sb_shared(struct super_block *sb, aufs_bindex_t btgt,
+			aufs_bindex_t bend)
+{
+	aufs_bindex_t bindex;
+	struct super_block *tgt_sb = au_sbr_sb(sb, btgt);
+
+	for (bindex = 0; bindex < btgt; bindex++)
+		if (unlikely(tgt_sb == au_sbr_sb(sb, bindex)))
+			return bindex;
+	for (bindex++; bindex <= bend; bindex++)
+		if (unlikely(tgt_sb == au_sbr_sb(sb, bindex)))
+			return bindex;
+	return -1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * initialize the xinofile for the specified branch @br
+ * at the place/path where @base_file indicates.
+ * test whether another branch is on the same filesystem or not,
+ * if @do_test is true.
+ */
+int au_xino_br(struct super_block *sb, struct au_branch *br, ino_t h_ino,
+	       struct file *base_file, int do_test)
+{
+	int err;
+	ino_t ino;
+	aufs_bindex_t bend, bindex;
+	struct au_branch *shared_br, *b;
+	struct file *file;
+	struct super_block *tgt_sb;
+
+	shared_br = NULL;
+	bend = au_sbend(sb);
+	if (do_test) {
+		tgt_sb = br->br_mnt->mnt_sb;
+		for (bindex = 0; bindex <= bend; bindex++) {
+			b = au_sbr(sb, bindex);
+			if (tgt_sb == b->br_mnt->mnt_sb) {
+				shared_br = b;
+				break;
+			}
+		}
+	}
+
+	if (!shared_br || !shared_br->br_xino.xi_file) {
+		struct au_xino_lock_dir ldir;
+
+		au_xino_lock_dir(sb, base_file, &ldir);
+		/* mnt_want_write() is unnecessary here */
+		file = au_xino_create2(base_file, NULL);
+		au_xino_unlock_dir(&ldir);
+		err = PTR_ERR(file);
+		if (IS_ERR(file))
+			goto out;
+		br->br_xino.xi_file = file;
+	} else {
+		br->br_xino.xi_file = shared_br->br_xino.xi_file;
+		get_file(br->br_xino.xi_file);
+	}
+
+	ino = AUFS_ROOT_INO;
+	err = au_xino_do_write(au_sbi(sb)->si_xwrite, br->br_xino.xi_file,
+			       h_ino, ino);
+	if (!err)
+		return 0; /* success */
+
+
+ out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* trucate a xino bitmap file */
+
+/* todo: slow */
+static int do_xib_restore(struct super_block *sb, struct file *file, void *page)
+{
+	int err, bit;
+	ssize_t sz;
+	unsigned long pindex;
+	loff_t pos, pend;
+	struct au_sbinfo *sbinfo;
+	au_readf_t func;
+	ino_t *ino;
+	unsigned long *p;
+
+	err = 0;
+	sbinfo = au_sbi(sb);
+	p = sbinfo->si_xib_buf;
+	func = sbinfo->si_xread;
+	pend = i_size_read(file->f_dentry->d_inode);
+	pos = 0;
+	while (pos < pend) {
+		sz = xino_fread(func, file, page, PAGE_SIZE, &pos);
+		err = sz;
+		if (unlikely(sz <= 0))
+			goto out;
+
+		err = 0;
+		for (ino = page; sz > 0; ino++, sz -= sizeof(ino)) {
+			if (unlikely(*ino < AUFS_FIRST_INO))
+				continue;
+
+			xib_calc_bit(*ino, &pindex, &bit);
+			AuDebugOn(page_bits <= bit);
+			err = xib_pindex(sb, pindex);
+			if (!err)
+				set_bit(bit, p);
+			else
+				goto out;
+		}
+	}
+
+ out:
+	return err;
+}
+
+static int xib_restore(struct super_block *sb)
+{
+	int err;
+	aufs_bindex_t bindex, bend;
+	void *page;
+
+	err = -ENOMEM;
+	page = (void *)__get_free_page(GFP_NOFS);
+	if (unlikely(!page))
+		goto out;
+
+	err = 0;
+	bend = au_sbend(sb);
+	for (bindex = 0; !err && bindex <= bend; bindex++)
+		if (!bindex || is_sb_shared(sb, bindex, bindex - 1) < 0)
+			err = do_xib_restore
+				(sb, au_sbr(sb, bindex)->br_xino.xi_file, page);
+		else
+			AuDbg("b%d\n", bindex);
+	free_page((unsigned long)page);
+
+ out:
+	return err;
+}
+
+int au_xib_trunc(struct super_block *sb)
+{
+	int err;
+	ssize_t sz;
+	loff_t pos;
+	struct au_xino_lock_dir ldir;
+	struct au_sbinfo *sbinfo;
+	unsigned long *p;
+	struct file *file;
+
+	err = 0;
+	sbinfo = au_sbi(sb);
+	if (!au_opt_test(sbinfo->si_mntflags, XINO))
+		goto out;
+
+	file = sbinfo->si_xib;
+	if (i_size_read(file->f_dentry->d_inode) <= PAGE_SIZE)
+		goto out;
+
+	au_xino_lock_dir(sb, file, &ldir);
+	/* mnt_want_write() is unnecessary here */
+	file = au_xino_create2(sbinfo->si_xib, NULL);
+	au_xino_unlock_dir(&ldir);
+	err = PTR_ERR(file);
+	if (IS_ERR(file))
+		goto out;
+	fput(sbinfo->si_xib);
+	sbinfo->si_xib = file;
+
+	p = sbinfo->si_xib_buf;
+	memset(p, 0, PAGE_SIZE);
+	pos = 0;
+	sz = xino_fwrite(sbinfo->si_xwrite, sbinfo->si_xib, p, PAGE_SIZE, &pos);
+	if (unlikely(sz != PAGE_SIZE)) {
+		err = sz;
+		AuIOErr("err %d\n", err);
+		if (sz >= 0)
+			err = -EIO;
+		goto out;
+	}
+
+	mutex_lock(&sbinfo->si_xib_mtx);
+	/* mnt_want_write() is unnecessary here */
+	err = xib_restore(sb);
+	mutex_unlock(&sbinfo->si_xib_mtx);
+
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * xino mount option handlers
+ */
+static au_readf_t find_readf(struct file *h_file)
+{
+	const struct file_operations *fop = h_file->f_op;
+
+	if (fop) {
+		if (fop->read)
+			return fop->read;
+		if (fop->aio_read)
+			return do_sync_read;
+	}
+	return ERR_PTR(-ENOSYS);
+}
+
+static au_writef_t find_writef(struct file *h_file)
+{
+	const struct file_operations *fop = h_file->f_op;
+
+	if (fop) {
+		if (fop->write)
+			return fop->write;
+		if (fop->aio_write)
+			return do_sync_write;
+	}
+	return ERR_PTR(-ENOSYS);
+}
+
+/* xino bitmap */
+static void xino_clear_xib(struct super_block *sb)
+{
+	struct au_sbinfo *sbinfo;
+
+	sbinfo = au_sbi(sb);
+	sbinfo->si_xread = NULL;
+	sbinfo->si_xwrite = NULL;
+	if (sbinfo->si_xib)
+		fput(sbinfo->si_xib);
+	sbinfo->si_xib = NULL;
+	free_page((unsigned long)sbinfo->si_xib_buf);
+	sbinfo->si_xib_buf = NULL;
+}
+
+static int au_xino_set_xib(struct super_block *sb, struct file *base)
+{
+	int err;
+	loff_t pos;
+	struct au_sbinfo *sbinfo;
+	struct file *file;
+
+	sbinfo = au_sbi(sb);
+	file = au_xino_create2(base, sbinfo->si_xib);
+	err = PTR_ERR(file);
+	if (IS_ERR(file))
+		goto out;
+	if (sbinfo->si_xib)
+		fput(sbinfo->si_xib);
+	sbinfo->si_xib = file;
+	sbinfo->si_xread = find_readf(file);
+	sbinfo->si_xwrite = find_writef(file);
+
+	err = -ENOMEM;
+	if (!sbinfo->si_xib_buf)
+		sbinfo->si_xib_buf = (void *)get_zeroed_page(GFP_NOFS);
+	if (unlikely(!sbinfo->si_xib_buf))
+		goto out_unset;
+
+	sbinfo->si_xib_last_pindex = 0;
+	sbinfo->si_xib_next_bit = 0;
+	if (i_size_read(file->f_dentry->d_inode) < PAGE_SIZE) {
+		pos = 0;
+		err = xino_fwrite(sbinfo->si_xwrite, file, sbinfo->si_xib_buf,
+				  PAGE_SIZE, &pos);
+		if (unlikely(err != PAGE_SIZE))
+			goto out_free;
+	}
+	err = 0;
+	goto out; /* success */
+
+ out_free:
+	free_page((unsigned long)sbinfo->si_xib_buf);
+	sbinfo->si_xib_buf = NULL;
+	if (err >= 0)
+		err = -EIO;
+ out_unset:
+	fput(sbinfo->si_xib);
+	sbinfo->si_xib = NULL;
+	sbinfo->si_xread = NULL;
+	sbinfo->si_xwrite = NULL;
+ out:
+	return err;
+}
+
+/* xino for each branch */
+static void xino_clear_br(struct super_block *sb)
+{
+	aufs_bindex_t bindex, bend;
+	struct au_branch *br;
+
+	bend = au_sbend(sb);
+	for (bindex = 0; bindex <= bend; bindex++) {
+		br = au_sbr(sb, bindex);
+		if (!br || !br->br_xino.xi_file)
+			continue;
+
+		fput(br->br_xino.xi_file);
+		br->br_xino.xi_file = NULL;
+	}
+}
+
+static int au_xino_set_br(struct super_block *sb, struct file *base)
+{
+	int err;
+	ino_t ino;
+	aufs_bindex_t bindex, bend, bshared;
+	struct {
+		struct file *old, *new;
+	} *fpair, *p;
+	struct au_branch *br;
+	struct inode *inode;
+	au_writef_t writef;
+
+	err = -ENOMEM;
+	bend = au_sbend(sb);
+	fpair = kcalloc(bend + 1, sizeof(*fpair), GFP_NOFS);
+	if (unlikely(!fpair))
+		goto out;
+
+	inode = sb->s_root->d_inode;
+	ino = AUFS_ROOT_INO;
+	writef = au_sbi(sb)->si_xwrite;
+	for (bindex = 0, p = fpair; bindex <= bend; bindex++, p++) {
+		br = au_sbr(sb, bindex);
+		bshared = is_sb_shared(sb, bindex, bindex - 1);
+		if (bshared >= 0) {
+			/* shared xino */
+			*p = fpair[bshared];
+			get_file(p->new);
+		}
+
+		if (!p->new) {
+			/* new xino */
+			p->old = br->br_xino.xi_file;
+			p->new = au_xino_create2(base, br->br_xino.xi_file);
+			err = PTR_ERR(p->new);
+			if (IS_ERR(p->new)) {
+				p->new = NULL;
+				goto out_pair;
+			}
+		}
+
+		err = au_xino_do_write(writef, p->new,
+				       au_h_iptr(inode, bindex)->i_ino, ino);
+		if (unlikely(err))
+			goto out_pair;
+	}
+
+	for (bindex = 0, p = fpair; bindex <= bend; bindex++, p++) {
+		br = au_sbr(sb, bindex);
+		if (br->br_xino.xi_file)
+			fput(br->br_xino.xi_file);
+		get_file(p->new);
+		br->br_xino.xi_file = p->new;
+	}
+
+ out_pair:
+	for (bindex = 0, p = fpair; bindex <= bend; bindex++, p++)
+		if (p->new)
+			fput(p->new);
+		else
+			break;
+	kfree(fpair);
+ out:
+	return err;
+}
+
+void au_xino_clr(struct super_block *sb)
+{
+	struct au_sbinfo *sbinfo;
+
+	xino_clear_xib(sb);
+	xino_clear_br(sb);
+	sbinfo = au_sbi(sb);
+	/* lvalue, do not call au_mntflags() */
+	au_opt_clr(sbinfo->si_mntflags, XINO);
+}
+
+int au_xino_set(struct super_block *sb, struct au_opt_xino *xino, int remount)
+{
+	int err, skip;
+	struct dentry *parent, *cur_parent;
+	struct qstr *dname, *cur_name;
+	struct file *cur_xino;
+	struct inode *dir;
+	struct au_sbinfo *sbinfo;
+
+	err = 0;
+	sbinfo = au_sbi(sb);
+	parent = dget_parent(xino->file->f_dentry);
+	if (remount) {
+		skip = 0;
+		dname = &xino->file->f_dentry->d_name;
+		cur_xino = sbinfo->si_xib;
+		if (cur_xino) {
+			cur_parent = dget_parent(cur_xino->f_dentry);
+			cur_name = &cur_xino->f_dentry->d_name;
+			skip = (cur_parent == parent
+				&& dname->len == cur_name->len
+				&& !memcmp(dname->name, cur_name->name,
+					   dname->len));
+			dput(cur_parent);
+		}
+		if (skip)
+			goto out;
+	}
+
+	au_opt_set(sbinfo->si_mntflags, XINO);
+	dir = parent->d_inode;
+	mutex_lock_nested(&dir->i_mutex, AuLsc_I_PARENT);
+	/* mnt_want_write() is unnecessary here */
+	err = au_xino_set_xib(sb, xino->file);
+	if (!err)
+		err = au_xino_set_br(sb, xino->file);
+	mutex_unlock(&dir->i_mutex);
+	if (!err)
+		goto out; /* success */
+
+	/* reset all */
+	AuIOErr("failed creating xino(%d).\n", err);
+
+ out:
+	dput(parent);
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * create a xinofile at the default place/path.
+ */
+struct file *au_xino_def(struct super_block *sb)
+{
+	struct file *file;
+	char *page, *p;
+	struct au_branch *br;
+	struct super_block *h_sb;
+	struct path path;
+	aufs_bindex_t bend, bindex, bwr;
+
+	br = NULL;
+	bend = au_sbend(sb);
+	bwr = -1;
+	for (bindex = 0; bindex <= bend; bindex++) {
+		br = au_sbr(sb, bindex);
+		if (au_br_writable(br->br_perm)
+		    && !au_test_fs_bad_xino(br->br_mnt->mnt_sb)) {
+			bwr = bindex;
+			break;
+		}
+	}
+
+	if (bwr >= 0) {
+		file = ERR_PTR(-ENOMEM);
+		page = __getname();
+		if (unlikely(!page))
+			goto out;
+		path.mnt = br->br_mnt;
+		path.dentry = au_h_dptr(sb->s_root, bwr);
+		p = d_path(&path, page, PATH_MAX - sizeof(AUFS_XINO_FNAME));
+		file = (void *)p;
+		if (!IS_ERR(p)) {
+			strcat(p, "/" AUFS_XINO_FNAME);
+			AuDbg("%s\n", p);
+			file = au_xino_create(sb, p, /*silent*/0);
+			if (!IS_ERR(file))
+				au_xino_brid_set(sb, br->br_id);
+		}
+		__putname(page);
+	} else {
+		file = au_xino_create(sb, AUFS_XINO_DEFPATH, /*silent*/0);
+		if (IS_ERR(file))
+			goto out;
+		h_sb = file->f_dentry->d_sb;
+		if (unlikely(au_test_fs_bad_xino(h_sb))) {
+			AuErr("xino doesn't support %s(%s)\n",
+			      AUFS_XINO_DEFPATH, au_sbtype(h_sb));
+			fput(file);
+			file = ERR_PTR(-EINVAL);
+		}
+		if (!IS_ERR(file))
+			au_xino_brid_set(sb, -1);
+	}
+
+ out:
+	return file;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_xino_path(struct seq_file *seq, struct file *file)
+{
+	int err;
+
+	err = au_seq_path(seq, &file->f_path);
+	if (unlikely(err < 0))
+		goto out;
+
+	err = 0;
+#define Deleted "\\040(deleted)"
+	seq->count -= sizeof(Deleted) - 1;
+	AuDebugOn(memcmp(seq->buf + seq->count, Deleted,
+			 sizeof(Deleted) - 1));
+#undef Deleted
+
+ out:
+	return err;
+}
-- 
1.6.1.284.g5dc13

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