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-rw-r--r--ubuntu/aufs/sysfs.c257
1 files changed, 257 insertions, 0 deletions
diff --git a/ubuntu/aufs/sysfs.c b/ubuntu/aufs/sysfs.c
new file mode 100644
index 000000000000..f72519dac361
--- /dev/null
+++ b/ubuntu/aufs/sysfs.c
@@ -0,0 +1,257 @@
+/*
+ * Copyright (C) 2005-2012 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
+ */
+
+/*
+ * sysfs interface
+ */
+
+#include <linux/seq_file.h>
+#include "aufs.h"
+
+#ifdef CONFIG_AUFS_FS_MODULE
+/* this entry violates the "one line per file" policy of sysfs */
+static ssize_t config_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ ssize_t err;
+ static char *conf =
+/* this file is generated at compiling */
+#include "conf.str"
+ ;
+
+ err = snprintf(buf, PAGE_SIZE, conf);
+ if (unlikely(err >= PAGE_SIZE))
+ err = -EFBIG;
+ return err;
+}
+
+static struct kobj_attribute au_config_attr = __ATTR_RO(config);
+#endif
+
+static struct attribute *au_attr[] = {
+#ifdef CONFIG_AUFS_FS_MODULE
+ &au_config_attr.attr,
+#endif
+ NULL, /* need to NULL terminate the list of attributes */
+};
+
+static struct attribute_group sysaufs_attr_group_body = {
+ .attrs = au_attr
+};
+
+struct attribute_group *sysaufs_attr_group = &sysaufs_attr_group_body;
+
+/* ---------------------------------------------------------------------- */
+
+int sysaufs_si_xi_path(struct seq_file *seq, struct super_block *sb)
+{
+ int err;
+
+ SiMustAnyLock(sb);
+
+ err = 0;
+ if (au_opt_test(au_mntflags(sb), XINO)) {
+ err = au_xino_path(seq, au_sbi(sb)->si_xib);
+ seq_putc(seq, '\n');
+ }
+ return err;
+}
+
+/*
+ * the lifetime of branch is independent from the entry under sysfs.
+ * sysfs handles the lifetime of the entry, and never call ->show() after it is
+ * unlinked.
+ */
+static int sysaufs_si_br(struct seq_file *seq, struct super_block *sb,
+ aufs_bindex_t bindex)
+{
+ int err;
+ struct path path;
+ struct dentry *root;
+ struct au_branch *br;
+ char *perm;
+
+ AuDbg("b%d\n", bindex);
+
+ err = 0;
+ root = sb->s_root;
+ di_read_lock_parent(root, !AuLock_IR);
+ br = au_sbr(sb, bindex);
+ path.mnt = br->br_mnt;
+ path.dentry = au_h_dptr(root, bindex);
+ au_seq_path(seq, &path);
+ di_read_unlock(root, !AuLock_IR);
+ perm = au_optstr_br_perm(br->br_perm);
+ if (perm) {
+ err = seq_printf(seq, "=%s\n", perm);
+ kfree(perm);
+ if (err == -1)
+ err = -E2BIG;
+ } else
+ err = -ENOMEM;
+ return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct seq_file *au_seq(char *p, ssize_t len)
+{
+ struct seq_file *seq;
+
+ seq = kzalloc(sizeof(*seq), GFP_NOFS);
+ if (seq) {
+ /* mutex_init(&seq.lock); */
+ seq->buf = p;
+ seq->size = len;
+ return seq; /* success */
+ }
+
+ seq = ERR_PTR(-ENOMEM);
+ return seq;
+}
+
+#define SysaufsBr_PREFIX "br"
+
+/* todo: file size may exceed PAGE_SIZE */
+ssize_t sysaufs_si_show(struct kobject *kobj, struct attribute *attr,
+ char *buf)
+{
+ ssize_t err;
+ long l;
+ aufs_bindex_t bend;
+ struct au_sbinfo *sbinfo;
+ struct super_block *sb;
+ struct seq_file *seq;
+ char *name;
+ struct attribute **cattr;
+
+ sbinfo = container_of(kobj, struct au_sbinfo, si_kobj);
+ sb = sbinfo->si_sb;
+
+ /*
+ * prevent a race condition between sysfs and aufs.
+ * for instance, sysfs_file_read() calls sysfs_get_active_two() which
+ * prohibits maintaining the sysfs entries.
+ * hew we acquire read lock after sysfs_get_active_two().
+ * on the other hand, the remount process may maintain the sysfs/aufs
+ * entries after acquiring write lock.
+ * it can cause a deadlock.
+ * simply we gave up processing read here.
+ */
+ err = -EBUSY;
+ if (unlikely(!si_noflush_read_trylock(sb)))
+ goto out;
+
+ seq = au_seq(buf, PAGE_SIZE);
+ err = PTR_ERR(seq);
+ if (IS_ERR(seq))
+ goto out_unlock;
+
+ name = (void *)attr->name;
+ cattr = sysaufs_si_attrs;
+ while (*cattr) {
+ if (!strcmp(name, (*cattr)->name)) {
+ err = container_of(*cattr, struct sysaufs_si_attr, attr)
+ ->show(seq, sb);
+ goto out_seq;
+ }
+ cattr++;
+ }
+
+ bend = au_sbend(sb);
+ if (!strncmp(name, SysaufsBr_PREFIX, sizeof(SysaufsBr_PREFIX) - 1)) {
+ name += sizeof(SysaufsBr_PREFIX) - 1;
+ err = kstrtol(name, 10, &l);
+ if (!err) {
+ if (l <= bend)
+ err = sysaufs_si_br(seq, sb, (aufs_bindex_t)l);
+ else
+ err = -ENOENT;
+ }
+ goto out_seq;
+ }
+ BUG();
+
+out_seq:
+ if (!err) {
+ err = seq->count;
+ /* sysfs limit */
+ if (unlikely(err == PAGE_SIZE))
+ err = -EFBIG;
+ }
+ kfree(seq);
+out_unlock:
+ si_read_unlock(sb);
+out:
+ return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void sysaufs_br_init(struct au_branch *br)
+{
+ struct attribute *attr = &br->br_attr;
+
+ sysfs_attr_init(attr);
+ attr->name = br->br_name;
+ attr->mode = S_IRUGO;
+}
+
+void sysaufs_brs_del(struct super_block *sb, aufs_bindex_t bindex)
+{
+ struct au_branch *br;
+ struct kobject *kobj;
+ aufs_bindex_t bend;
+
+ dbgaufs_brs_del(sb, bindex);
+
+ if (!sysaufs_brs)
+ return;
+
+ kobj = &au_sbi(sb)->si_kobj;
+ bend = au_sbend(sb);
+ for (; bindex <= bend; bindex++) {
+ br = au_sbr(sb, bindex);
+ sysfs_remove_file(kobj, &br->br_attr);
+ }
+}
+
+void sysaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex)
+{
+ int err;
+ aufs_bindex_t bend;
+ struct kobject *kobj;
+ struct au_branch *br;
+
+ dbgaufs_brs_add(sb, bindex);
+
+ if (!sysaufs_brs)
+ return;
+
+ kobj = &au_sbi(sb)->si_kobj;
+ bend = au_sbend(sb);
+ for (; bindex <= bend; bindex++) {
+ br = au_sbr(sb, bindex);
+ snprintf(br->br_name, sizeof(br->br_name), SysaufsBr_PREFIX
+ "%d", bindex);
+ err = sysfs_create_file(kobj, &br->br_attr);
+ if (unlikely(err))
+ pr_warning("failed %s under sysfs(%d)\n",
+ br->br_name, err);
+ }
+}
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