linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Mark Fasheh <mfasheh@suse.de>
To: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org,
	Mark Fasheh <mfasheh@suse.de>
Subject: [PATCH 01/76] vfs: Introduce struct fs_view
Date: Tue,  8 May 2018 11:03:21 -0700	[thread overview]
Message-ID: <20180508180436.716-2-mfasheh@suse.de> (raw)
In-Reply-To: <20180508180436.716-1-mfasheh@suse.de>

We want to de-couple some items from struct super_block, in particular those
that provide a 'fiew' into an fs.

Introduce a small struct, fs_view to contain these fields. This first patch
has a mostly empty fs_view. We do however, link it into the VFS:

Each super_block gets a default fs_view which is filled in via the
usual superblock intialization methods.

struct inode is updated to point to an fs_view structure via a new
'i_view' pointer, which replaces i_sb.

A filesystem can now optionally provide their own fs_view to point i_view
to.

So we don't lose our link from inode to superblock, fs_view gets
an embedded super_block pointer. A helper function, inode_sb() is
introduced to make getting the superblock from an inode less clunky.

Filesystems need no functional changes, and the only additional memory
usage here is the added pointer on struct super_block.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/inode.c         |  2 +-
 fs/super.c         |  1 +
 include/linux/fs.h | 21 ++++++++++++++++++++-
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index ef362364d396..4f08fdc2c60f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -133,7 +133,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 	static const struct file_operations no_open_fops = {.open = no_open};
 	struct address_space *const mapping = &inode->i_data;
 
-	inode->i_sb = sb;
+	inode->i_view = &sb->s_view;
 	inode->i_blkbits = sb->s_blocksize_bits;
 	inode->i_flags = 0;
 	atomic_set(&inode->i_count, 1);
diff --git a/fs/super.c b/fs/super.c
index 672538ca9831..5258a57d410a 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -245,6 +245,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
 	s->s_op = &default_op;
 	s->s_time_gran = 1000000000;
 	s->cleancache_poolid = CLEANCACHE_NO_POOL;
+	s->s_view.v_sb = s;
 
 	s->s_shrink.seeks = DEFAULT_SEEKS;
 	s->s_shrink.scan_objects = super_cache_scan;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c6baf767619e..4561cb9156d4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -580,7 +580,7 @@ struct inode {
 #endif
 
 	const struct inode_operations	*i_op;
-	struct super_block	*i_sb;
+	struct fs_view		*i_view;
 	struct address_space	*i_mapping;
 
 #ifdef CONFIG_SECURITY
@@ -1340,6 +1340,24 @@ struct sb_writers {
 	struct percpu_rw_semaphore	rw_sem[SB_FREEZE_LEVELS];
 };
 
+/*
+ * "View" into a filesystem. Allows us to abstract out those
+ * superblock fields which change between the roots on a given
+ * filesystem. Most filesystems can ignore this - inodes are pointed
+ * to the default view 's_view' during initialization.
+ *
+ * A file system with multiple roots should allocate a view structure
+ * per root and point each inodes view pointer to it in iget.
+ */
+struct fs_view {
+	struct super_block	*v_sb;
+};
+
+static inline struct super_block *inode_sb(const struct inode *inode)
+{
+	return inode->i_view->v_sb;
+}
+
 struct super_block {
 	struct list_head	s_list;		/* Keep this first */
 	dev_t			s_dev;		/* search index; _not_ kdev_t */
@@ -1358,6 +1376,7 @@ struct super_block {
 	struct rw_semaphore	s_umount;
 	int			s_count;
 	atomic_t		s_active;
+	struct fs_view		s_view;		/* default view into the fs */
 #ifdef CONFIG_SECURITY
 	void                    *s_security;
 #endif
-- 
2.15.1

  reply	other threads:[~2018-05-08 18:03 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-08 18:03 [RFC][PATCH 0/76] vfs: 'views' for filesystems with more than one root Mark Fasheh
2018-05-08 18:03 ` Mark Fasheh [this message]
2018-05-08 18:03 ` [PATCH 02/76] arch: Use inode_sb() helper instead of inode->i_sb Mark Fasheh
2018-05-08 18:03 ` [PATCH 03/76] drivers: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 04/76] fs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 05/76] include: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 06/76] ipc: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 07/76] kernel: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 08/76] mm: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 09/76] net: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 10/76] security: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 11/76] fs/9p: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 12/76] fs/adfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 13/76] fs/affs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 14/76] fs/afs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 15/76] fs/autofs4: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 16/76] fs/befs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 17/76] fs/bfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 18/76] fs/btrfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 19/76] fs/ceph: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 20/76] fs/cifs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 21/76] fs/coda: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 22/76] fs/configfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 23/76] fs/cramfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 24/76] fs/crypto: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 25/76] fs/ecryptfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 26/76] fs/efivarfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 27/76] fs/efs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 28/76] fs/exofs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 29/76] fs/exportfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 30/76] fs/ext2: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 31/76] fs/ext4: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 32/76] fs/f2fs: " Mark Fasheh
2018-05-10 10:10   ` Chao Yu
2018-05-08 18:03 ` [PATCH 33/76] fs/fat: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 34/76] fs/freevxfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 35/76] fs/fuse: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 36/76] fs/gfs2: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 37/76] fs/hfs: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 38/76] fs/hfsplus: " Mark Fasheh
2018-05-08 18:03 ` [PATCH 39/76] fs/hostfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 40/76] fs/hpfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 41/76] fs/hugetlbfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 42/76] fs/isofs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 43/76] fs/jbd2: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 44/76] fs/jffs2: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 45/76] fs/jfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 46/76] fs/kernfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 47/76] fs/lockd: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 48/76] fs/minix: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 49/76] fs/nfsd: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 50/76] fs/nfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 51/76] fs/nilfs2: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 52/76] fs/notify: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 53/76] fs/ntfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 54/76] fs/ocfs2: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 55/76] fs/omfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 56/76] fs/openpromfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 57/76] fs/orangefs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 58/76] fs/overlayfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 59/76] fs/proc: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 60/76] fs/qnx4: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 61/76] fs/qnx6: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 62/76] fs/quota: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 63/76] fs/ramfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 64/76] fs/read: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 65/76] fs/reiserfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 66/76] fs/romfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 67/76] fs/squashfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 68/76] fs/sysv: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 69/76] fs/ubifs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 70/76] fs/udf: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 71/76] fs/ufs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 72/76] fs/xfs: " Mark Fasheh
2018-05-08 18:04 ` [PATCH 73/76] vfs: Move s_dev to to struct fs_view Mark Fasheh
2018-05-08 18:04 ` [PATCH 74/76] fs: Use fs_view device from struct inode Mark Fasheh
2018-05-08 18:04 ` [PATCH 75/76] fs: Use fs view device from struct super_block Mark Fasheh
2018-05-08 18:04 ` [PATCH 76/76] btrfs: Use fs_view in roots, point inodes to it Mark Fasheh
2018-05-08 23:38 ` [RFC][PATCH 0/76] vfs: 'views' for filesystems with more than one root Dave Chinner
2018-05-09  2:06   ` Jeff Mahoney
2018-05-09  6:41     ` Dave Chinner
2018-06-05 20:17       ` Jeff Mahoney
2018-06-06  9:49         ` Amir Goldstein
2018-06-06 20:42           ` Mark Fasheh
2018-06-07  6:06             ` Amir Goldstein
2018-06-07 20:44               ` Mark Fasheh
2018-06-06 21:19           ` Jeff Mahoney
2018-06-07  6:17             ` Amir Goldstein

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180508180436.716-2-mfasheh@suse.de \
    --to=mfasheh@suse.de \
    --cc=linux-btrfs@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH 01/76] vfs: Introduce struct fs_view' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox