reiserfs: simplify xattr internal file lookups/opens

The xattr file open/lookup code is needlessly complex.  We can use
vfs-level operations to perform the same work, and also simplify the
locking constraints.  The locking advantages will be exploited in future
patches.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeff Mahoney 2009-03-30 14:02:34 -04:00 committed by Linus Torvalds
parent a72bdb1cd2
commit 6c17675e1e

View file

@ -44,100 +44,123 @@
#include <net/checksum.h>
#include <linux/smp_lock.h>
#include <linux/stat.h>
#include <linux/quotaops.h>
#define FL_READONLY 128
#define FL_DIR_SEM_HELD 256
#define PRIVROOT_NAME ".reiserfs_priv"
#define XAROOT_NAME "xattrs"
/* Returns the dentry referring to the root of the extended attribute
* directory tree. If it has already been retrieved, it is used. If it
* hasn't been created and the flags indicate creation is allowed, we
* attempt to create it. On error, we return a pointer-encoded error.
*/
static struct dentry *get_xa_root(struct super_block *sb, int flags)
/* Helpers for inode ops. We do this so that we don't have all the VFS
* overhead and also for proper i_mutex annotation.
* dir->i_mutex must be held for all of them. */
static int xattr_create(struct inode *dir, struct dentry *dentry, int mode)
{
struct dentry *privroot = dget(REISERFS_SB(sb)->priv_root);
struct dentry *xaroot;
/* This needs to be created at mount-time */
if (!privroot)
return ERR_PTR(-ENODATA);
mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
if (REISERFS_SB(sb)->xattr_root) {
xaroot = dget(REISERFS_SB(sb)->xattr_root);
goto out;
}
xaroot = lookup_one_len(XAROOT_NAME, privroot, strlen(XAROOT_NAME));
if (IS_ERR(xaroot)) {
goto out;
} else if (!xaroot->d_inode) {
int err = -ENODATA;
if (flags == 0 || flags & XATTR_CREATE)
err = privroot->d_inode->i_op->mkdir(privroot->d_inode,
xaroot, 0700);
if (err) {
dput(xaroot);
xaroot = ERR_PTR(err);
goto out;
}
}
REISERFS_SB(sb)->xattr_root = dget(xaroot);
out:
mutex_unlock(&privroot->d_inode->i_mutex);
dput(privroot);
return xaroot;
BUG_ON(!mutex_is_locked(&dir->i_mutex));
DQUOT_INIT(dir);
return dir->i_op->create(dir, dentry, mode, NULL);
}
static int xattr_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
BUG_ON(!mutex_is_locked(&dir->i_mutex));
DQUOT_INIT(dir);
return dir->i_op->mkdir(dir, dentry, mode);
}
/* We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr
* mutation ops aren't called during rename or splace, which are the
* only other users of I_MUTEX_CHILD. It violates the ordering, but that's
* better than allocating another subclass just for this code. */
static int xattr_unlink(struct inode *dir, struct dentry *dentry)
{
int error;
BUG_ON(!mutex_is_locked(&dir->i_mutex));
DQUOT_INIT(dir);
mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
error = dir->i_op->unlink(dir, dentry);
mutex_unlock(&dentry->d_inode->i_mutex);
if (!error)
d_delete(dentry);
return error;
}
static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
{
int error;
BUG_ON(!mutex_is_locked(&dir->i_mutex));
DQUOT_INIT(dir);
mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
dentry_unhash(dentry);
error = dir->i_op->rmdir(dir, dentry);
if (!error)
dentry->d_inode->i_flags |= S_DEAD;
mutex_unlock(&dentry->d_inode->i_mutex);
if (!error)
d_delete(dentry);
dput(dentry);
return error;
}
#define xattr_may_create(flags) (!flags || flags & XATTR_CREATE)
/* Returns and possibly creates the xattr dir. */
static struct dentry *lookup_or_create_dir(struct dentry *parent,
const char *name, int flags)
{
struct dentry *dentry;
BUG_ON(!parent);
dentry = lookup_one_len(name, parent, strlen(name));
if (IS_ERR(dentry))
return dentry;
else if (!dentry->d_inode) {
int err = -ENODATA;
if (xattr_may_create(flags)) {
mutex_lock_nested(&parent->d_inode->i_mutex,
I_MUTEX_XATTR);
err = xattr_mkdir(parent->d_inode, dentry, 0700);
mutex_unlock(&parent->d_inode->i_mutex);
}
if (err) {
dput(dentry);
dentry = ERR_PTR(err);
}
}
return dentry;
}
static struct dentry *open_xa_root(struct super_block *sb, int flags)
{
struct dentry *privroot = REISERFS_SB(sb)->priv_root;
if (!privroot)
return ERR_PTR(-ENODATA);
return lookup_or_create_dir(privroot, XAROOT_NAME, flags);
}
/* Opens the directory corresponding to the inode's extended attribute store.
* If flags allow, the tree to the directory may be created. If creation is
* prohibited, -ENODATA is returned. */
static struct dentry *open_xa_dir(const struct inode *inode, int flags)
{
struct dentry *xaroot, *xadir;
char namebuf[17];
xaroot = get_xa_root(inode->i_sb, flags);
xaroot = open_xa_root(inode->i_sb, flags);
if (IS_ERR(xaroot))
return xaroot;
/* ok, we have xaroot open */
snprintf(namebuf, sizeof(namebuf), "%X.%X",
le32_to_cpu(INODE_PKEY(inode)->k_objectid),
inode->i_generation);
xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
if (IS_ERR(xadir)) {
dput(xaroot);
return xadir;
}
if (!xadir->d_inode) {
int err;
if (flags == 0 || flags & XATTR_CREATE) {
/* Although there is nothing else trying to create this directory,
* another directory with the same hash may be created, so we need
* to protect against that */
err =
xaroot->d_inode->i_op->mkdir(xaroot->d_inode, xadir,
0700);
if (err) {
dput(xaroot);
dput(xadir);
return ERR_PTR(err);
}
}
if (!xadir->d_inode) {
dput(xaroot);
dput(xadir);
return ERR_PTR(-ENODATA);
}
}
xadir = lookup_or_create_dir(xaroot, namebuf, flags);
dput(xaroot);
return xadir;
}
/*
@ -302,13 +325,11 @@ static
int xattr_readdir(struct inode *inode, filldir_t filler, void *buf)
{
int res = -ENOENT;
mutex_lock_nested(&inode->i_mutex, I_MUTEX_XATTR);
if (!IS_DEADDIR(inode)) {
lock_kernel();
res = __xattr_readdir(inode, buf, filler);
unlock_kernel();
}
mutex_unlock(&inode->i_mutex);
return res;
}
@ -345,9 +366,7 @@ __reiserfs_xattr_del(struct dentry *xadir, const char *name, int namelen)
return -EIO;
}
err = dir->i_op->unlink(dir, dentry);
if (!err)
d_delete(dentry);
err = xattr_unlink(dir, dentry);
out_file:
dput(dentry);
@ -381,7 +400,7 @@ int reiserfs_delete_xattrs(struct inode *inode)
return 0;
reiserfs_read_lock_xattrs(inode->i_sb);
dir = open_xa_dir(inode, FL_READONLY);
dir = open_xa_dir(inode, XATTR_REPLACE);
reiserfs_read_unlock_xattrs(inode->i_sb);
if (IS_ERR(dir)) {
err = PTR_ERR(dir);
@ -391,25 +410,25 @@ int reiserfs_delete_xattrs(struct inode *inode)
return 0;
}
lock_kernel();
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
err = xattr_readdir(dir->d_inode, reiserfs_delete_xattrs_filler, dir);
if (err) {
unlock_kernel();
mutex_unlock(&dir->d_inode->i_mutex);
if (err)
goto out_dir;
}
/* Leftovers besides . and .. -- that's not good. */
if (dir->d_inode->i_nlink <= 2) {
root = get_xa_root(inode->i_sb, XATTR_REPLACE);
root = open_xa_root(inode->i_sb, XATTR_REPLACE);
reiserfs_write_lock_xattrs(inode->i_sb);
err = vfs_rmdir(root->d_inode, dir);
mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_XATTR);
err = xattr_rmdir(root->d_inode, dir);
mutex_unlock(&root->d_inode->i_mutex);
reiserfs_write_unlock_xattrs(inode->i_sb);
dput(root);
} else {
reiserfs_warning(inode->i_sb, "jdm-20006",
"Couldn't remove all entries in directory");
}
unlock_kernel();
out_dir:
dput(dir);
@ -445,8 +464,11 @@ reiserfs_chown_xattrs_filler(void *buf, const char *name, int namelen,
return -ENODATA;
}
if (!S_ISDIR(xafile->d_inode->i_mode))
if (!S_ISDIR(xafile->d_inode->i_mode)) {
mutex_lock_nested(&xafile->d_inode->i_mutex, I_MUTEX_CHILD);
err = notify_change(xafile, attrs);
mutex_unlock(&xafile->d_inode->i_mutex);
}
dput(xafile);
return err;
@ -464,38 +486,31 @@ int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
return 0;
reiserfs_read_lock_xattrs(inode->i_sb);
dir = open_xa_dir(inode, FL_READONLY);
dir = open_xa_dir(inode, XATTR_REPLACE);
reiserfs_read_unlock_xattrs(inode->i_sb);
if (IS_ERR(dir)) {
if (PTR_ERR(dir) != -ENODATA)
err = PTR_ERR(dir);
goto out;
} else if (!dir->d_inode) {
dput(dir);
goto out;
}
lock_kernel();
} else if (!dir->d_inode)
goto out_dir;
attrs->ia_valid &= (ATTR_UID | ATTR_GID | ATTR_CTIME);
buf.xadir = dir;
buf.attrs = attrs;
buf.inode = inode;
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
err = xattr_readdir(dir->d_inode, reiserfs_chown_xattrs_filler, &buf);
if (err) {
unlock_kernel();
goto out_dir;
}
err = notify_change(dir, attrs);
unlock_kernel();
if (!err)
err = notify_change(dir, attrs);
mutex_unlock(&dir->d_inode->i_mutex);
attrs->ia_valid = ia_valid;
out_dir:
dput(dir);
out:
attrs->ia_valid = ia_valid;
return err;
}
@ -513,47 +528,35 @@ static struct dentry *get_xa_file_dentry(const struct inode *inode,
int err = 0;
xadir = open_xa_dir(inode, flags);
if (IS_ERR(xadir)) {
if (IS_ERR(xadir))
return ERR_CAST(xadir);
} else if (xadir && !xadir->d_inode) {
dput(xadir);
return ERR_PTR(-ENODATA);
}
xafile = lookup_one_len(name, xadir, strlen(name));
if (IS_ERR(xafile)) {
dput(xadir);
return ERR_CAST(xafile);
}
if (xafile->d_inode) { /* file exists */
if (flags & XATTR_CREATE) {
err = -EEXIST;
dput(xafile);
goto out;
}
} else if (flags & XATTR_REPLACE || flags & FL_READONLY) {
err = PTR_ERR(xafile);
goto out;
} else {
/* inode->i_mutex is down, so nothing else can try to create
* the same xattr */
err = xadir->d_inode->i_op->create(xadir->d_inode, xafile,
0700 | S_IFREG, NULL);
}
if (err) {
dput(xafile);
goto out;
if (xafile->d_inode && (flags & XATTR_CREATE))
err = -EEXIST;
if (!xafile->d_inode) {
err = -ENODATA;
if (xattr_may_create(flags)) {
mutex_lock_nested(&xadir->d_inode->i_mutex,
I_MUTEX_XATTR);
err = xattr_create(xadir->d_inode, xafile,
0700|S_IFREG);
mutex_unlock(&xadir->d_inode->i_mutex);
}
}
if (err)
dput(xafile);
out:
dput(xadir);
if (err)
xafile = ERR_PTR(err);
else if (!xafile->d_inode) {
dput(xafile);
xafile = ERR_PTR(-ENODATA);
}
return ERR_PTR(err);
return xafile;
}
@ -633,6 +636,7 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
err = notify_change(dentry, &newattrs);
mutex_unlock(&dentry->d_inode->i_mutex);
if (err)
goto out_filp;
@ -692,7 +696,6 @@ reiserfs_xattr_set(struct inode *inode, const char *name, const void *buffer,
}
out_filp:
mutex_unlock(&dentry->d_inode->i_mutex);
dput(dentry);
out:
@ -722,7 +725,7 @@ reiserfs_xattr_get(const struct inode *inode, const char *name, void *buffer,
if (get_inode_sd_version(inode) == STAT_DATA_V1)
return -EOPNOTSUPP;
dentry = get_xa_file_dentry(inode, name, FL_READONLY);
dentry = get_xa_file_dentry(inode, name, XATTR_REPLACE);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
goto out;
@ -806,13 +809,15 @@ int reiserfs_xattr_del(struct inode *inode, const char *name)
struct dentry *dir;
int err;
dir = open_xa_dir(inode, FL_READONLY);
dir = open_xa_dir(inode, XATTR_REPLACE);
if (IS_ERR(dir)) {
err = PTR_ERR(dir);
goto out;
}
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
err = __reiserfs_xattr_del(dir, name, strlen(name));
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
if (!err) {
@ -826,6 +831,7 @@ int reiserfs_xattr_del(struct inode *inode, const char *name)
/* Actual operations that are exported to VFS-land */
static struct reiserfs_xattr_handler *find_xattr_handler_prefix(const char *);
/*
* Inode operation getxattr()
* Preliminary locking: we down dentry->d_inode->i_mutex
@ -978,7 +984,7 @@ ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
reiserfs_read_lock_xattr_i(dentry->d_inode);
reiserfs_read_lock_xattrs(dentry->d_sb);
dir = open_xa_dir(dentry->d_inode, FL_READONLY);
dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE);
reiserfs_read_unlock_xattrs(dentry->d_sb);
if (IS_ERR(dir)) {
err = PTR_ERR(dir);
@ -994,7 +1000,9 @@ ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
REISERFS_I(dentry->d_inode)->i_flags |= i_has_xattr_dir;
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
err = xattr_readdir(dir->d_inode, reiserfs_listxattr_filler, &buf);
mutex_unlock(&dir->d_inode->i_mutex);
if (err)
goto out_dir;
@ -1146,7 +1154,7 @@ static int create_privroot(struct dentry *dentry)
int err;
struct inode *inode = dentry->d_parent->d_inode;
mutex_lock_nested(&inode->i_mutex, I_MUTEX_XATTR);
err = inode->i_op->mkdir(inode, dentry, 0700);
err = xattr_mkdir(inode, dentry, 0700);
mutex_unlock(&inode->i_mutex);
if (err) {
dput(dentry);