[AUFS PATCH v2.6.26-rc2-mm1 16/39] aufs pseudo-link

[hooanon05]

From: Junjiro Okajima <hooanon05@xxxxxxxxxxx>

initial commit
pseudo-link is a logical hardlink over branches or different filesystems.

Signed-off-by: Junjiro Okajima <hooanon05@xxxxxxxxxxx>
---
 fs/aufs/plink.c |  344 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 344 insertions(+), 0 deletions(-)
 create mode 100644 fs/aufs/plink.c

diff --git a/fs/aufs/plink.c b/fs/aufs/plink.c
new file mode 100644
index 0000000..7197d7c
--- /dev/null
+++ b/fs/aufs/plink.c
@@ -0,0 +1,344 @@
+/*
+ * Copyright (C) 2007-2008 Junjiro 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
+ */
+
+/*
+ * pseudo-link
+ */
+
+#include "aufs.h"
+
+struct pseudo_link {
+	struct list_head list;
+	struct inode *inode;
+};
+
+#ifdef CONFIG_AUFS_DEBUG
+void au_plink_list(struct super_block *sb)
+{
+	struct au_sbinfo *sbinfo;
+	struct list_head *plink_list;
+	struct pseudo_link *plink;
+
+	AuTraceEnter();
+	SiMustAnyLock(sb);
+	sbinfo = au_sbi(sb);
+	AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+	plink_list = &sbinfo->si_plink;
+	spin_lock(&sbinfo->si_plink_lock);
+	list_for_each_entry(plink, plink_list, list)
+		AuDbg("%lu\n", plink->inode->i_ino);
+	spin_unlock(&sbinfo->si_plink_lock);
+}
+#endif
+
+int au_plink_test(struct super_block *sb, struct inode *inode)
+{
+	int found;
+	struct au_sbinfo *sbinfo;
+	struct list_head *plink_list;
+	struct pseudo_link *plink;
+
+	LKTRTrace("i%lu\n", inode->i_ino);
+	SiMustAnyLock(sb);
+	sbinfo = au_sbi(sb);
+	AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+	found = 0;
+	plink_list = &sbinfo->si_plink;
+	spin_lock(&sbinfo->si_plink_lock);
+	list_for_each_entry(plink, plink_list, list)
+		if (plink->inode == inode) {
+			found = 1;
+			break;
+		}
+	spin_unlock(&sbinfo->si_plink_lock);
+	return found;
+}
+
+/* 20 is max digits length of ulong 64 */
+#define PLINK_NAME_LEN	((20 + 1) * 2)
+
+static int plink_name(char *name, int len, struct inode *inode,
+		      aufs_bindex_t bindex)
+{
+	int rlen;
+	struct inode *h_inode;
+
+	LKTRTrace("i%lu, b%d\n", inode->i_ino, bindex);
+	AuDebugOn(len != PLINK_NAME_LEN);
+	h_inode = au_h_iptr(inode, bindex);
+	AuDebugOn(!h_inode);
+	rlen = snprintf(name, len, "%lu.%lu", inode->i_ino, h_inode->i_ino);
+	AuDebugOn(rlen >= len);
+	return rlen;
+}
+
+struct dentry *au_plink_lkup(struct super_block *sb, aufs_bindex_t bindex,
+			     struct inode *inode)
+{
+	struct dentry *h_dentry, *h_parent;
+	struct au_branch *br;
+	struct inode *h_dir;
+	char tgtname[PLINK_NAME_LEN];
+	int len;
+	struct au_ndx ndx = {
+		.flags	= 0,
+		.nd	= NULL,
+		/* .br	= NULL */
+	};
+
+	LKTRTrace("b%d, i%lu\n", bindex, inode->i_ino);
+	br = au_sbr(sb, bindex);
+	h_parent = br->br_plink;
+	AuDebugOn(!h_parent);
+	h_dir = h_parent->d_inode;
+	AuDebugOn(!h_dir);
+
+	len = plink_name(tgtname, sizeof(tgtname), inode, bindex);
+
+	/* always superio. */
+	ndx.nfsmnt = au_do_nfsmnt(br->br_mnt);
+	mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_CHILD2);
+	h_dentry = au_sio_lkup_one(tgtname, h_parent, len, &ndx);
+	mutex_unlock(&h_dir->i_mutex);
+	return h_dentry;
+}
+
+static int do_whplink(char *tgt, int len, struct dentry *h_parent,
+		      struct dentry *h_dentry, struct vfsmount *nfsmnt,
+		      struct super_block *sb)
+{
+	int err, dlgt;
+	struct dentry *h_tgt;
+	struct inode *h_dir;
+	struct vfsub_args vargs;
+	struct au_ndx ndx = {
+		.nfsmnt	= nfsmnt,
+		.flags	= 0,
+		.nd	= NULL,
+		/* .br	= NULL */
+	};
+
+	dlgt = !!au_opt_test_dlgt(au_mntflags(sb));
+	if (unlikely(dlgt))
+		au_fset_ndx(ndx.flags, DLGT);
+	h_tgt = au_lkup_one(tgt, h_parent, len, &ndx);
+	err = PTR_ERR(h_tgt);
+	if (IS_ERR(h_tgt))
+		goto out;
+
+	err = 0;
+	vfsub_args_init(&vargs, NULL, dlgt, 0);
+	h_dir = h_parent->d_inode;
+	if (unlikely(h_tgt->d_inode && h_tgt->d_inode != h_dentry->d_inode))
+		err = vfsub_unlink(h_dir, h_tgt, &vargs);
+	if (!err && !h_tgt->d_inode) {
+		err = vfsub_link(h_dentry, h_dir, h_tgt, dlgt);
+		/* todo: unnecessary? */
+		/* inc_nlink(inode); */
+	}
+	dput(h_tgt);
+
+ out:
+	AuTraceErr(err);
+	return err;
+}
+
+struct do_whplink_args {
+	int *errp;
+	char *tgt;
+	int len;
+	struct dentry *h_parent;
+	struct dentry *h_dentry;
+	struct vfsmount *nfsmnt;
+	struct super_block *sb;
+};
+
+static void call_do_whplink(void *args)
+{
+	struct do_whplink_args *a = args;
+	*a->errp = do_whplink(a->tgt, a->len, a->h_parent, a->h_dentry,
+			      a->nfsmnt, a->sb);
+}
+
+static int whplink(struct dentry *h_dentry, struct inode *inode,
+		   aufs_bindex_t bindex, struct super_block *sb)
+{
+	int err, len, wkq_err;
+	struct au_branch *br;
+	struct dentry *h_parent;
+	struct inode *h_dir;
+	char tgtname[PLINK_NAME_LEN];
+
+	LKTRTrace("%.*s\n", AuDLNPair(h_dentry));
+	br = au_sbr(inode->i_sb, bindex);
+	h_parent = br->br_plink;
+	AuDebugOn(!h_parent);
+	h_dir = h_parent->d_inode;
+	AuDebugOn(!h_dir);
+
+	len = plink_name(tgtname, sizeof(tgtname), inode, bindex);
+
+	/* always superio. */
+	mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_CHILD2);
+	if (!au_test_wkq(current)) {
+		struct do_whplink_args args = {
+			.errp		= &err,
+			.tgt		= tgtname,
+			.len		= len,
+			.h_parent	= h_parent,
+			.h_dentry	= h_dentry,
+			.nfsmnt		= au_do_nfsmnt(br->br_mnt),
+			.sb		= sb
+		};
+		wkq_err = au_wkq_wait(call_do_whplink, &args, /*dlgt*/0);
+		if (unlikely(wkq_err))
+			err = wkq_err;
+	} else
+		err = do_whplink(tgtname, len, h_parent, h_dentry,
+				 au_do_nfsmnt(br->br_mnt), sb);
+	mutex_unlock(&h_dir->i_mutex);
+
+	AuTraceErr(err);
+	return err;
+}
+
+void au_plink_append(struct super_block *sb, struct inode *inode,
+		     struct dentry *h_dentry, aufs_bindex_t bindex)
+{
+	struct au_sbinfo *sbinfo;
+	struct list_head *plink_list;
+	struct pseudo_link *plink;
+	int found, err, cnt;
+
+	LKTRTrace("i%lu\n", inode->i_ino);
+	SiMustAnyLock(sb);
+	sbinfo = au_sbi(sb);
+	AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+	cnt = 0;
+	found = 0;
+	plink_list = &sbinfo->si_plink;
+	spin_lock(&sbinfo->si_plink_lock);
+	list_for_each_entry(plink, plink_list, list) {
+		cnt++;
+		if (plink->inode == inode) {
+			found = 1;
+			break;
+		}
+	}
+
+	err = 0;
+	if (!found) {
+		plink = kmalloc(sizeof(*plink), GFP_ATOMIC);
+		if (plink) {
+			plink->inode = igrab(inode);
+			list_add(&plink->list, plink_list);
+			cnt++;
+		} else
+			err = -ENOMEM;
+	}
+	spin_unlock(&sbinfo->si_plink_lock);
+
+	if (!err)
+		err = whplink(h_dentry, inode, bindex, sb);
+
+	if (unlikely(cnt > AUFS_PLINK_WARN))
+		AuWarn1("unexpectedly many pseudo links, %d\n", cnt);
+	if (unlikely(err))
+		AuWarn("err %d, damaged pseudo link. ignored.\n", err);
+}
+
+static void do_put_plink(struct pseudo_link *plink, int do_del)
+{
+	AuTraceEnter();
+
+	iput(plink->inode);
+	if (do_del)
+		list_del(&plink->list);
+	kfree(plink);
+}
+
+void au_plink_put(struct super_block *sb)
+{
+	struct au_sbinfo *sbinfo;
+	struct list_head *plink_list;
+	struct pseudo_link *plink, *tmp;
+
+	AuTraceEnter();
+	SiMustWriteLock(sb);
+	sbinfo = au_sbi(sb);
+	AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+	plink_list = &sbinfo->si_plink;
+	/* spin_lock(&sbinfo->si_plink_lock); */
+	list_for_each_entry_safe(plink, tmp, plink_list, list)
+		do_put_plink(plink, 0);
+	INIT_LIST_HEAD(plink_list);
+	/* spin_unlock(&sbinfo->si_plink_lock); */
+}
+
+void au_plink_half_refresh(struct super_block *sb, aufs_bindex_t br_id)
+{
+	struct au_sbinfo *sbinfo;
+	struct list_head *plink_list;
+	struct pseudo_link *plink, *tmp;
+	struct inode *inode;
+	aufs_bindex_t bstart, bend, bindex;
+	int do_put;
+
+	AuTraceEnter();
+	SiMustWriteLock(sb);
+	sbinfo = au_sbi(sb);
+	AuDebugOn(!au_opt_test(au_mntflags(sb), PLINK));
+
+	plink_list = &sbinfo->si_plink;
+	/* spin_lock(&sbinfo->si_plink_lock); */
+	list_for_each_entry_safe(plink, tmp, plink_list, list) {
+		do_put = 0;
+		inode = igrab(plink->inode);
+		ii_write_lock_child(inode);
+		bstart = au_ibstart(inode);
+		bend = au_ibend(inode);
+		if (bstart >= 0) {
+			for (bindex = bstart; bindex <= bend; bindex++) {
+				if (!au_h_iptr(inode, bindex)
+				    || au_ii_br_id(inode, bindex) != br_id)
+					continue;
+				au_set_h_iptr(inode, bindex, NULL, 0);
+				do_put = 1;
+				break;
+			}
+		} else
+			do_put_plink(plink, 1);
+
+		if (do_put) {
+			for (bindex = bstart; bindex <= bend; bindex++)
+				if (au_h_iptr(inode, bindex)) {
+					do_put = 0;
+					break;
+				}
+			if (do_put)
+				do_put_plink(plink, 1);
+		}
+		ii_write_unlock(inode);
+		iput(inode);
+	}
+	/* spin_unlock(&sbinfo->si_plink_lock); */
+}
-- 
1.5.5.1.308.g1fbb5.dirty

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