Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755309Ab3GJXqw (ORCPT ); Wed, 10 Jul 2013 19:46:52 -0400 Received: from mail-ea0-f170.google.com ([209.85.215.170]:43430 "EHLO mail-ea0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754725Ab3GJXqQ (ORCPT ); Wed, 10 Jul 2013 19:46:16 -0400 From: David Herrmann To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, Alexander Viro , Dave Airlie , linux-fsdevel@vger.kernel.org, Andrew Morton , Daniel Vetter , David Herrmann Subject: [PATCH 1/2] anon_inodes: allow external inode allocations Date: Thu, 11 Jul 2013 01:45:29 +0200 Message-Id: <1373499930-5055-2-git-send-email-dh.herrmann@gmail.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1373499930-5055-1-git-send-email-dh.herrmann@gmail.com> References: <1373499930-5055-1-git-send-email-dh.herrmann@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4000 Lines: 111 DRM core shares a single address_space across all inodes that belong to the same DRM device. This allows efficient unmapping of user-space mappings during buffer destruction. However, there is no easy way to get a shared address_space for DRM devices during initialization. Therefore, we currently delay this step until the first ->open() and save the given inode for future use. This causes ugly delayed initialization throughout the DRM core. TTM devices end up without a dev_mapping pointer and we have to carefully respect any underlying filesystem implementation so we don't corrupt the inode->i_mapping and inode->i_data fields. We can avoid this if we were allowed to allocate an anonymous inode for each DRM device. We only have to set file->f_mapping during ->open() and no longer need to adjust inode mappings. As fs/anon_inodes.c already provides a minimal internal FS mount, we extend it to also provide anonymous inodes for use in drivers like DRM. Signed-off-by: David Herrmann --- fs/anon_inodes.c | 36 +++++++++++++++++++++++++++++------- include/linux/anon_inodes.h | 1 + 2 files changed, 30 insertions(+), 7 deletions(-) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 47a65df..7d8a80a 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -25,6 +25,7 @@ static struct vfsmount *anon_inode_mnt __read_mostly; static struct inode *anon_inode_inode; static const struct file_operations anon_inode_fops; +static struct dentry *anon_inode_root; /* * anon_inodefs_dname() is called from d_path(). @@ -87,19 +88,18 @@ static struct inode *anon_inode_mkinode(struct super_block *s) static struct dentry *anon_inodefs_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { - struct dentry *root; - root = mount_pseudo(fs_type, "anon_inode:", NULL, + anon_inode_root = mount_pseudo(fs_type, "anon_inode:", NULL, &anon_inodefs_dentry_operations, ANON_INODE_FS_MAGIC); - if (!IS_ERR(root)) { - struct super_block *s = root->d_sb; + if (!IS_ERR(anon_inode_root)) { + struct super_block *s = anon_inode_root->d_sb; anon_inode_inode = anon_inode_mkinode(s); if (IS_ERR(anon_inode_inode)) { - dput(root); + dput(anon_inode_root); deactivate_locked_super(s); - root = ERR_CAST(anon_inode_inode); + anon_inode_root = ERR_CAST(anon_inode_inode); } } - return root; + return anon_inode_root; } static struct file_system_type anon_inode_fs_type = { @@ -219,6 +219,28 @@ err_put_unused_fd: } EXPORT_SYMBOL_GPL(anon_inode_getfd); +/** + * anon_inode_new - create private anonymous inode + * + * Creates a new inode on the anonymous inode FS for driver's use. The inode has + * it's own address_space compared to the shared anon_inode_inode. It can be + * used in situations where user-space mappings have to be shared across + * different files but no backing inode is available. + * + * Call iput(inode) to release the inode. + * + * RETURNS: + * New inode on success, error pointer on failure. + */ +struct inode *anon_inode_new(void) +{ + if (IS_ERR(anon_inode_root)) + return ERR_CAST(anon_inode_root); + + return anon_inode_mkinode(anon_inode_root->d_sb); +} +EXPORT_SYMBOL_GPL(anon_inode_new); + static int __init anon_inode_init(void) { int error; diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h index 8013a45..ddbd67f 100644 --- a/include/linux/anon_inodes.h +++ b/include/linux/anon_inodes.h @@ -15,6 +15,7 @@ struct file *anon_inode_getfile(const char *name, void *priv, int flags); int anon_inode_getfd(const char *name, const struct file_operations *fops, void *priv, int flags); +struct inode *anon_inode_new(void); #endif /* _LINUX_ANON_INODES_H */ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/