From patchwork Tue Oct 20 05:50:21 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 54884 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n9K5otNh004793 for ; Tue, 20 Oct 2009 05:50:55 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752835AbZJTFuT (ORCPT ); Tue, 20 Oct 2009 01:50:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752785AbZJTFuS (ORCPT ); Tue, 20 Oct 2009 01:50:18 -0400 Received: from palinux.external.hp.com ([192.25.206.14]:49377 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752484AbZJTFuR (ORCPT ); Tue, 20 Oct 2009 01:50:17 -0400 Received: by mail.parisc-linux.org (Postfix, from userid 26919) id AB046494009; Mon, 19 Oct 2009 23:50:21 -0600 (MDT) Date: Mon, 19 Oct 2009 23:50:21 -0600 From: Matthew Wilcox To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Jesse Barnes , linux-pci@vger.kernel.org Subject: [PATCH 2/3] Sysfs: Allow directories to be populated dynamically Message-ID: <20091020055021.GE29158@parisc-linux.org> References: <20091020054740.GC29158@parisc-linux.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20091020054740.GC29158@parisc-linux.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 5fad489..e32a11d 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -294,9 +294,13 @@ void release_sysfs_dirent(struct sysfs_dirent * sd) goto repeat; } -static void sysfs_d_iput(struct dentry * dentry, struct inode * inode) +static void sysfs_d_iput(struct dentry *dentry, struct inode *inode) { - struct sysfs_dirent * sd = dentry->d_fsdata; + struct sysfs_dirent *sd = dentry->d_fsdata; + + if ((sysfs_type(sd) == SYSFS_DIR) && sd->s_dir.depopulate) + sd->s_dir.depopulate(dentry, sd); + sd->s_flags &= ~SYSFS_FLAG_POPULATED; sysfs_put(sd); iput(inode); @@ -574,6 +578,22 @@ repeat: iput(inode); } +void sysfs_kill_removed_dirents(struct sysfs_addrm_cxt *acxt) +{ + /* kill removed sysfs_dirents */ + while (acxt->removed) { + struct sysfs_dirent *sd = acxt->removed; + + acxt->removed = sd->s_sibling; + sd->s_sibling = NULL; + + sysfs_drop_dentry(sd); + sysfs_deactivate(sd); + unmap_bin_file(sd); + sysfs_put(sd); + } +} + /** * sysfs_addrm_finish - finish up sysfs_dirent add/remove * @acxt: addrm context to finish up @@ -600,18 +620,7 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) iput(inode); } - /* kill removed sysfs_dirents */ - while (acxt->removed) { - struct sysfs_dirent *sd = acxt->removed; - - acxt->removed = sd->s_sibling; - sd->s_sibling = NULL; - - sysfs_drop_dentry(sd); - sysfs_deactivate(sd); - unmap_bin_file(sd); - sysfs_put(sd); - } + sysfs_kill_removed_dirents(acxt); } /** @@ -731,6 +740,17 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, mutex_lock(&sysfs_mutex); + if (!(parent_sd->s_flags & SYSFS_FLAG_POPULATED)) { + if (parent_sd->s_dir.populate) { + int err = parent_sd->s_dir.populate(dentry->d_parent, + parent_sd); + if (err) { + ret = ERR_PTR(err); + goto out_unlock; + } + } + parent_sd->s_flags |= SYSFS_FLAG_POPULATED; + } sd = sysfs_find_dirent(parent_sd, dentry->d_name.name); /* no such entry */ @@ -1012,7 +1032,6 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) return 0; } - const struct file_operations sysfs_dir_operations = { .read = generic_read_dir, .readdir = sysfs_readdir, diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c index 0c4d342..37ac584 100644 --- a/fs/sysfs/group.c +++ b/fs/sysfs/group.c @@ -16,6 +16,102 @@ #include "sysfs.h" +/* + * i_mutex is not held, but this inode is on its way out of the system, so + * nobody gets to mess with it. We can't take the sysfs_mutex here as it + * leads to a deadlock scenario where it's held in a path that can run + * reclaim, and this function can be called from reclaim context. I guess + * prayer is the only solution here (other than splitting sysfs_mutex) + */ +void sysfs_depopulate_group(struct dentry *dentry, + const struct attribute_group *grp) + +{ + struct sysfs_dirent *dir_sd = dentry->d_fsdata; + struct sysfs_addrm_cxt acxt; + struct attribute **attrp; + + memset(&acxt, 0, sizeof(acxt)); + acxt.parent_sd = dir_sd; + acxt.parent_inode = dentry->d_inode; + + for (attrp = grp->attrs; *attrp; attrp++) { + struct attribute *attr = *attrp; + struct sysfs_dirent *sd; + + sd = sysfs_find_dirent(dir_sd, attr->name); + if (sd) + sysfs_remove_one(&acxt, sd); + } + + sysfs_kill_removed_dirents(&acxt); +} +EXPORT_SYMBOL(sysfs_depopulate_group); + +/* + * inode->i_mutex is held by the VFS, and sysfs_mutex is held by + * sysfs_lookup, so there's no need to call sysfs_addrm_start/finish here. + * Nor is there a need to mess around with reference counts. + */ +int sysfs_populate_group(struct dentry *dentry, + const struct attribute_group *grp) + +{ + struct sysfs_dirent *dir_sd = dentry->d_fsdata; + struct kobject *kobj = dir_sd->s_dir.kobj; + struct sysfs_addrm_cxt acxt; + struct attribute **attrp; + int i = 0, error = 0; + + memset(&acxt, 0, sizeof(acxt)); + acxt.parent_sd = dir_sd; + acxt.parent_inode = dentry->d_inode; + + for (attrp = grp->attrs; *attrp; attrp++) { + struct attribute *attr = *attrp; + mode_t mode = attr->mode; + struct sysfs_dirent *sd; + + if (grp->is_visible) { + mode_t vis = grp->is_visible(kobj, attr, i++); + if (!vis) + continue; + mode |= vis; + } + + sd = sysfs_new_dirent(attr->name, mode, SYSFS_KOBJ_ATTR); + if (!sd) { + error = -ENOMEM; + break; + } + sd->s_attr.attr = (void *)attr; + + error = sysfs_add_one(&acxt, sd); + if (error) { + sysfs_put(sd); + break; + } + } + if (error) + sysfs_depopulate_group(dentry, grp); + return error; +} +EXPORT_SYMBOL(sysfs_populate_group); + +static +int group_populate(struct dentry *dentry, struct sysfs_dirent *sd) +{ + struct attribute_group *grp = sd->s_dir.data; + return sysfs_populate_group(dentry, grp); +} + +static +void group_depopulate(struct dentry *dentry, struct sysfs_dirent *sd) +{ + struct attribute_group *grp = sd->s_dir.data; + sysfs_depopulate_group(dentry, grp); +} + static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj, const struct attribute_group *grp) { @@ -32,6 +128,10 @@ static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj, struct attribute *const* attr; int error = 0, i; + /* Directory isn't currently instantiated; nothing to do */ + if (!(dir_sd->s_flags & SYSFS_FLAG_POPULATED)) + return 0; + for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) { mode_t mode = 0; @@ -55,7 +155,6 @@ static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj, return error; } - static int internal_create_group(struct kobject *kobj, int update, const struct attribute_group *grp) { @@ -82,10 +181,18 @@ static int internal_create_group(struct kobject *kobj, int update, } else { sd = sysfs_get(kobj->sd); } - error = create_files(sd, kobj, grp, update); - if (error) { - if (grp->name) + + error = 0; + if (update) { + error = create_files(sd, kobj, grp, update); + if (error && grp->name) sysfs_remove_subdir(sd); + } else if (!sd->s_dir.populate) { + sd->s_dir.populate = group_populate; + sd->s_dir.depopulate = group_depopulate; + sd->s_dir.data = (void *)grp; + } else if (sd->s_dir.populate != group_populate) { + error = -EEXIST; } sysfs_put(sd); return error; diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index af4c4e7..13843fa 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -17,6 +17,9 @@ struct sysfs_elem_dir { struct kobject *kobj; /* children list starts here and goes through sd->s_sibling */ struct sysfs_dirent *children; + int (*populate)(struct dentry *, struct sysfs_dirent *); + void (*depopulate)(struct dentry *, struct sysfs_dirent *); + void *data; }; struct sysfs_elem_symlink { @@ -77,6 +80,7 @@ struct sysfs_dirent { #define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK) #define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK +#define SYSFS_FLAG_POPULATED 0x0100 #define SYSFS_FLAG_REMOVED 0x0200 static inline unsigned int sysfs_type(struct sysfs_dirent *sd) @@ -120,6 +124,7 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd); int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd); void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd); void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt); +void sysfs_kill_removed_dirents(struct sysfs_addrm_cxt *acxt); struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name);