* Abstract
A subtree of a directory tree T is a tree consisting of a directory
(the subtree root) in T and all of its descendants in T.
*NOTE*: User is allowed to break pure subtree hierarchy via manual
id manipulation.
Subtree subtrees assumptions:
(1) Each inode has an id. This id is persistently stored inside
inode (xattr, usually inside ibody)
(2) Subtree id is inherent from parent directory
This feature is similar to project-id in XFS. One may assign some id to
a subtree. Each entry from the subtree may be accounted in directory
subtree quota. Will appear in later patches.
* Disk layout
Subtree id is stored on disk inside xattr usually inside ibody.
Xattr is used only as a data storage, It has not user visible xattr
interface.
* User interface
Subtree id is accessible via generic xattr interface "system.subtree"
* Notes
ext4_setattr interface to subtreeid: Semantically subtree id must being changed
similar to uid/gid, but subtree id is stored inside xattr so on-disk
structures updates is not that trivial, so I've move subtree change
logic to separate function.
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
---
fs/ext4/Kconfig | 12 +++
fs/ext4/Makefile | 1 +
fs/ext4/ext4.h | 3 +
fs/ext4/ialloc.c | 6 ++
fs/ext4/inode.c | 4 +
fs/ext4/subtree.c | 215 +++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/subtree.h | 45 +++++++++++
fs/ext4/super.c | 7 ++
fs/ext4/xattr.c | 7 ++
fs/ext4/xattr.h | 2 +
10 files changed, 302 insertions(+), 0 deletions(-)
create mode 100644 fs/ext4/subtree.c
create mode 100644 fs/ext4/subtree.h
diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
index c22f170..f571168 100644
--- a/fs/ext4/Kconfig
+++ b/fs/ext4/Kconfig
@@ -77,6 +77,18 @@ config EXT4_FS_SECURITY
If you are not using a security module that requires using
extended attributes for file security labels, say N.
+config EXT4_SUBTREE
+ bool "Ext4 subtree id support"
+ select SUBTREE
+ depends on EXT4_FS_XATTR
+ help
+ Enables subtree inode identifier support for ext4 filesystem.
+ This feature allow to assign extended inode's identifier similar to
+ uid/gid. Value is stored in xattr "system.subtree" and may be used
+ as additional quota limit.
+
+ If unsure, say N.
+
config EXT4_DEBUG
bool "EXT4 debugging support"
depends on EXT4_FS
diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 56fd8f8..df0a54c 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -12,3 +12,4 @@ ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ext4-$(CONFIG_EXT4_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o
ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
+ext4-$(CONFIG_EXT4_SUBTREE) += subtree.o
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index cfc4e01..f831210 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -925,6 +925,9 @@ struct ext4_inode_info {
/* Precomputed uuid+inum+igen checksum for seeding inode checksums */
__u32 i_csum_seed;
+#ifdef CONFIG_EXT4_SUBTREE
+ __u32 i_subtree;
+#endif
};
/*
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index d48e8b1..ff73fea 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -28,6 +28,7 @@
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"
+#include "subtree.h"
#include <trace/events/ext4.h>
@@ -898,6 +899,8 @@ got:
ei->i_extra_isize = EXT4_SB(sb)->s_want_extra_isize;
+ ext4_set_subtree(inode, ext4_get_subtree(dir));
+
ret = inode;
dquot_initialize(inode);
err = dquot_alloc_inode(inode);
@@ -911,6 +914,9 @@ got:
err = ext4_init_security(handle, inode, dir, qstr);
if (err)
goto fail_free_drop;
+ err = ext4_subtree_init(handle, inode);
+ if (err)
+ goto fail_free_drop;
if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
/* set extent flag only for directory, file and normal symlink*/
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 02bc8cb..caf72f8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -42,6 +42,7 @@
#include "xattr.h"
#include "acl.h"
#include "truncate.h"
+#include "subtree.h"
#include <trace/events/ext4.h>
@@ -3870,6 +3871,9 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
}
if (ret)
goto bad_inode;
+ ret = ext4_subtree_read(inode);
+ if (ret)
+ goto bad_inode;
if (S_ISREG(inode->i_mode)) {
inode->i_op = &ext4_file_inode_operations;
diff --git a/fs/ext4/subtree.c b/fs/ext4/subtree.c
new file mode 100644
index 0000000..0486740
--- /dev/null
+++ b/fs/ext4/subtree.c
@@ -0,0 +1,215 @@
+/*
+ * linux/fs/ext4/subtree.c
+ *
+ * Copyright (C) 2012 Parallels Inc
+ * Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
+ */
+
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/capability.h>
+#include <linux/fs.h>
+#include <linux/quotaops.h>
+#include "ext4_jbd2.h"
+#include "ext4.h"
+#include "xattr.h"
+#include "subtree.h"
+
+/*
+ * Subtree assumptions:
+ * (1) Each inode has subtree id. This id is persistently stored inside
+ * inode's xattr, usually inside ibody
+ * (2) Subtree id is inherent from parent directory
+ */
+
+/*
+ * Read subtree id from inode's xattr
+ * Locking: none
+ */
+int ext4_subtree_xattr_read(struct inode *inode, unsigned int *subtree)
+{
+ __le32 dsk_subtree;
+ int retval;
+
+ retval = ext4_xattr_get(inode, EXT4_XATTR_INDEX_SUBTREE, "",
+ &dsk_subtree, sizeof(dsk_subtree));
+ if (retval > 0) {
+ if (retval != sizeof(dsk_subtree))
+ return -EIO;
+ else
+ retval = 0;
+ }
+ *subtree = le32_to_cpu(dsk_subtree);
+ return retval;
+}
+
+/*
+ * Save subtree id to inode's xattr
+ * Locking: none
+ */
+int ext4_subtree_xattr_write(handle_t *handle, struct inode *inode,
+ unsigned int subtree, int xflags)
+{
+ __le32 dskid = cpu_to_le32(subtree);
+ int retval;
+
+ retval = ext4_xattr_set_handle(handle,
+ inode, EXT4_XATTR_INDEX_SUBTREE, "",
+ &dskid, sizeof(dskid), xflags);
+ if (retval > 0) {
+ if (retval != sizeof(dskid))
+ retval = -EIO;
+ else
+ retval = 0;
+ }
+ return retval;
+}
+
+/*
+ * Change subtree id.
+ * Called under inode->i_mutex
+ */
+int ext4_subtree_change(struct inode *inode, unsigned int new_subtree)
+{
+ /*
+ * One data_trans_blocks chunk for xattr update.
+ * One quota_trans_blocks chunk for quota transfer, and one
+ * quota_trans_block chunk for emergency quota rollback transfer,
+ * because quota rollback may result new quota blocks allocation.
+ */
+ unsigned credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
+ EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb) * 2;
+ int ret, ret2 = 0;
+ unsigned retries = 0;
+ handle_t *handle;
+ struct dquot *dquot[MAXQUOTAS] = {};
+ int old_id = ext4_get_subtree(inode);
+
+ dquot_initialize(inode);
+ dquot[SBTRQUOTA] = dqget(inode->i_sb, new_subtree, SBTRQUOTA);
+retry:
+ handle = ext4_journal_start(inode, credits);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ ext4_std_error(inode->i_sb, ret);
+ goto out;
+ }
+ /* Inode may not have subtree xattr yet. Create it explicitly */
+ ret = ext4_subtree_xattr_write(handle, inode, old_id, XATTR_CREATE);
+ if (ret == -EEXIST)
+ ret = 0;
+ if (ret) {
+ ret2 = ext4_journal_stop(handle);
+ if (ret2)
+ ret = ret2;
+ if (ret == -ENOSPC &&
+ ext4_should_retry_alloc(inode->i_sb, &retries))
+ goto retry;
+ }
+#ifdef CONFIG_QUOTA
+ ret = __dquot_transfer(inode, dquot);
+ if (ret)
+ return ret;
+#endif
+ ret = ext4_subtree_xattr_write(handle, inode, new_subtree,
+ XATTR_REPLACE);
+ if (ret) {
+ /*
+ * Function may fail only due to fatal error, Nor than less
+ * we have try to rollback quota changes.
+ */
+#ifdef CONFIG_QUOTA
+ __dquot_transfer(inode, dquot);
+#endif
+ ext4_std_error(inode->i_sb, ret);
+
+ } else
+ ext4_set_subtree(inode, new_subtree);
+
+ ret2 = ext4_journal_stop(handle);
+out:
+ dqput(dquot[SBTRQUOTA]);
+ if (ret2)
+ ret = ret2;
+ return ret;
+}
+
+int ext4_subtree_read(struct inode *inode)
+{
+ int ret = 0;
+ int subtree = 0;
+
+ ret = ext4_subtree_xattr_read(inode, &subtree);
+ if (ret == -ENODATA) {
+ subtree = 0;
+ ret = 0;
+ }
+ if (!ret)
+ ext4_set_subtree(inode, subtree);
+ return ret;
+}
+
+/*
+ * Initialize the subtree xattr of a new inode. Called from ext4_new_inode.
+ *
+ * dir->i_mutex: down
+ * inode->i_mutex: up (access to inode is still exclusive)
+ * Note: caller must assign correct subtree id to inode before.
+ */
+int ext4_subtree_init(handle_t *handle, struct inode *inode)
+{
+ return ext4_subtree_xattr_write(handle, inode, EXT4_I(inode)->i_subtree,
+ XATTR_CREATE);
+}
+
+static size_t
+ext4_xattr_subtree_list(struct dentry *dentry, char *list, size_t list_size,
+ const char *name, size_t name_len, int type)
+{
+ if (list && XATTR_SUBTREE_LEN <= list_size)
+ memcpy(list, XATTR_SUBTREE, XATTR_SUBTREE_LEN);
+ return XATTR_SUBTREE_LEN;
+}
+
+static int
+ext4_xattr_subtree_get(struct dentry *dentry, const char *name,
+ void *buffer, size_t size, int type)
+{
+ int ret;
+ unsigned subtree;
+ char buf[32];
+
+ if (strcmp(name, "") != 0)
+ return -EINVAL;
+ ret = ext4_subtree_xattr_read(dentry->d_inode, &subtree);
+ if (ret)
+ return ret;
+ snprintf(buf, sizeof(buf)-1, "%u", subtree);
+ buf[31] = '\0';
+ strncpy(buffer, buf, size);
+ return strlen(buf);
+}
+
+static int
+ext4_xattr_subtree_set(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags, int type)
+{
+ unsigned int new_subtree;
+ int ret = 0;
+ char buf[11];
+ if (strcmp(name, "") != 0 || size + 1 > sizeof(buf))
+ return -EINVAL;
+ memcpy(buf, (char *)value, size);
+ buf[size] = '\0';
+ if (kstrtouint(buf, 10, &new_subtree))
+ return -EINVAL;
+ return ext4_subtree_change(dentry->d_inode, new_subtree);
+}
+
+const struct xattr_handler ext4_xattr_subtree_handler = {
+ .prefix = XATTR_SUBTREE,
+ .list = ext4_xattr_subtree_list,
+ .get = ext4_xattr_subtree_get,
+ .set = ext4_xattr_subtree_set,
+};
diff --git a/fs/ext4/subtree.h b/fs/ext4/subtree.h
new file mode 100644
index 0000000..362de80
--- /dev/null
+++ b/fs/ext4/subtree.h
@@ -0,0 +1,45 @@
+#include <linux/xattr.h>
+#include <linux/fs.h>
+
+#ifdef CONFIG_EXT4_SUBTREE
+extern int ext4_subtree_xattr_read(struct inode *inode, unsigned int *subtree);
+extern int ext4_subtree_xattr_write(handle_t *handle, struct inode *inode,
+ unsigned int subtree, int xflags);
+extern int ext4_subtree_init(handle_t *handle, struct inode *inode);
+extern int ext4_subtree_read(struct inode *inode);
+extern int ext4_subtree_change(struct inode *inode, unsigned int new_subtree);
+static inline u32 ext4_get_subtree(const struct inode *inode)
+{
+ const struct ext4_inode_info *ei =
+ container_of(inode, const struct ext4_inode_info, vfs_inode);
+ return ei->i_subtree;
+}
+static inline void ext4_set_subtree(struct inode *inode, u32 id)
+{
+ EXT4_I(inode)->i_subtree = id;
+}
+#else
+#define ext4_get_subtree(inode) do {} while (0)
+#define ext4_set_subtree(inode, id) do {} while (0)
+static inline int ext4_subtree_xattr_read(struct inode *inode, unsigned int *id)
+{
+ return -ENOTSUPP;
+}
+static inline int ext4_subtree_xattr_write(handle_t *h, struct inode *inode,
+ unsigned int subtree, int xflags)
+{
+ return -ENOTSUPP;
+}
+static inline int ext4_subtree_read(struct inode *inode)
+{
+ return 0;
+}
+static inline int ext4_subtree_change(struct inode *inode, unsigned int id)
+{
+ return -ENOTSUPP;
+}
+static inline int ext4_subtree_init(handle_t *handle, struct inode *inode)
+{
+ return 0;
+}
+#endif
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 84c7ba4..3599c95 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -50,6 +50,7 @@
#include "xattr.h"
#include "acl.h"
#include "mballoc.h"
+#include "subtree.h"
#define CREATE_TRACE_POINTS
#include <trace/events/ext4.h>
@@ -1185,6 +1186,9 @@ static const struct super_operations ext4_sops = {
.quota_write = ext4_quota_write,
#endif
.bdev_try_to_free_page = bdev_try_to_free_page,
+#ifdef CONFIG_EXT4_SUBTREE
+ .get_subtree = ext4_get_subtree,
+#endif
};
static const struct super_operations ext4_nojournal_sops = {
@@ -1204,6 +1208,9 @@ static const struct super_operations ext4_nojournal_sops = {
.quota_write = ext4_quota_write,
#endif
.bdev_try_to_free_page = bdev_try_to_free_page,
+#ifdef CONFIG_EXT4_SUBTREE
+ .get_subtree = ext4_get_subtree,
+#endif
};
static const struct export_operations ext4_export_ops = {
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index e56c9ed..7466544 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -107,6 +107,10 @@ static const struct xattr_handler *ext4_xattr_handler_map[] = {
#ifdef CONFIG_EXT4_FS_SECURITY
[EXT4_XATTR_INDEX_SECURITY] = &ext4_xattr_security_handler,
#endif
+#ifdef CONFIG_EXT4_SUBTREE
+ [EXT4_XATTR_INDEX_SUBTREE] = &ext4_xattr_subtree_handler,
+#endif
+
};
const struct xattr_handler *ext4_xattr_handlers[] = {
@@ -119,6 +123,9 @@ const struct xattr_handler *ext4_xattr_handlers[] = {
#ifdef CONFIG_EXT4_FS_SECURITY
&ext4_xattr_security_handler,
#endif
+#ifdef CONFIG_EXT4_SUBTREE
+ &ext4_xattr_subtree_handler,
+#endif
NULL
};
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 91f31ca..b207f35 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -21,6 +21,7 @@
#define EXT4_XATTR_INDEX_TRUSTED 4
#define EXT4_XATTR_INDEX_LUSTRE 5
#define EXT4_XATTR_INDEX_SECURITY 6
+#define EXT4_XATTR_INDEX_SUBTREE 7
struct ext4_xattr_header {
__le32 h_magic; /* magic number for identification */
@@ -72,6 +73,7 @@ extern const struct xattr_handler ext4_xattr_trusted_handler;
extern const struct xattr_handler ext4_xattr_acl_access_handler;
extern const struct xattr_handler ext4_xattr_acl_default_handler;
extern const struct xattr_handler ext4_xattr_security_handler;
+extern const struct xattr_handler ext4_xattr_subtree_handler;
extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
--
1.7.1
--
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