From 6c17675e1e02ebde220ef639a3fb1333928ec2f4 Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Mon, 30 Mar 2009 14:02:34 -0400 Subject: 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 Signed-off-by: Linus Torvalds --- fs/reiserfs/xattr.c | 262 +++++++++++++++++++++++++++------------------------- 1 file changed, 135 insertions(+), 127 deletions(-) (limited to 'fs/reiserfs') diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c index f9bcdd5750f7..57920a4df7a4 100644 --- a/fs/reiserfs/xattr.c +++ b/fs/reiserfs/xattr.c @@ -44,100 +44,123 @@ #include #include #include +#include -#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; + BUG_ON(!mutex_is_locked(&dir->i_mutex)); + DQUOT_INIT(dir); + return dir->i_op->create(dir, dentry, mode, NULL); +} - /* This needs to be created at mount-time */ - if (!privroot) - return ERR_PTR(-ENODATA); +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); +} - 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; - } +/* 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); - xaroot = lookup_one_len(XAROOT_NAME, privroot, strlen(XAROOT_NAME)); - if (IS_ERR(xaroot)) { - goto out; - } else if (!xaroot->d_inode) { + 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 (flags == 0 || flags & XATTR_CREATE) - err = privroot->d_inode->i_op->mkdir(privroot->d_inode, - xaroot, 0700); + + 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(xaroot); - xaroot = ERR_PTR(err); - goto out; + dput(dentry); + dentry = ERR_PTR(err); } } - REISERFS_SB(sb)->xattr_root = dget(xaroot); - out: - mutex_unlock(&privroot->d_inode->i_mutex); - dput(privroot); - return xaroot; + 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); + err = PTR_ERR(xafile); + goto out; } - if (xafile->d_inode) { /* file exists */ - if (flags & XATTR_CREATE) { - err = -EEXIST; - dput(xafile); - goto out; - } - } else if (flags & XATTR_REPLACE || flags & FL_READONLY) { - 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 (xafile->d_inode && (flags & XATTR_CREATE)) + err = -EEXIST; - if (err) { - dput(xafile); - goto out; + 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); -- cgit v1.2.2