2010-04-15 23:05:05

by Valerie Aurora

[permalink] [raw]
Subject: [PATCH 00/35] Union mounts - everything but the xattrs

This patch series implements union mounts for every system call
except:

- xattr-related calls
- fchmod()/fchown()/futimensat() on an fd

The copyup portion is a proof of concept based around union_path_nd(),
which looks up both the target <mnt,dentry> pair and its parent's. If
the parent is on a union mount, and the target is on a lower layer, we
copy up the target.

This patch set is very raw and could use even the most superficial
review. Just take a look at Erez's review from December to see how
low-hanging the fruit is on this one.

-VAL

Felix Fietkau (2):
whiteout: jffs2 whiteout support
fallthru: jffs2 fallthru support

Jan Blunck (13):
VFS: Make lookup_hash() return a struct path
XXX autofs4: Save autofs trigger's vfsmount in super block info
whiteout/NFSD: Don't return information about whiteouts to userspace
whiteout: Add vfs_whiteout() and whiteout inode operation
whiteout: Set S_OPAQUE inode flag when creating directories
whiteout: Allow removal of a directory with whiteouts
whiteout: tmpfs whiteout support
whiteout: Split of ext2_append_link() from ext2_add_link()
whiteout: ext2 whiteout support
union-mount: Introduce MNT_UNION and MS_UNION flags
union-mount: Introduce union_mount structure and basic operations
union-mount: Drive the union cache via dcache
union-mount: Call do_whiteout() on unlink and rmdir in unions

Valerie Aurora (20):
VFS: Add read-only users count to superblock
fallthru: Basic fallthru definitions
fallthru: ext2 fallthru support
fallthru: tmpfs fallthru support
union-mount: Writable overlays/union mounts documentation
union-mount: Implement union lookup
union-mount: Support for mounting union mount file systems
union-mount: Copy up directory entries on first readdir()
VFS: Split inode_permission() and create path_permission()
VFS: Create user_path_nd() to lookup both parent and target
union-mount: In-kernel copyup routines
union-mount: Implement union-aware access()/faccessat()
union-mount: Implement union-aware link()
union-mount: Implement union-aware rename()
union-mount: Implement union-aware writable open()
union-mount: Implement union-aware chown()
union-mount: Implement union-aware truncate()
union-mount: Implement union-aware chmod()/fchmodat()
union-mount: Implement union-aware lchown()
union-mount: Implement union-aware utimensat()

Documentation/filesystems/union-mounts.txt | 708 ++++++++++++++++++++++
Documentation/filesystems/vfs.txt | 16 +-
fs/Kconfig | 13 +
fs/Makefile | 1 +
fs/autofs4/autofs_i.h | 1 +
fs/autofs4/init.c | 11 +-
fs/autofs4/root.c | 6 +
fs/compat.c | 9 +
fs/dcache.c | 35 +-
fs/ext2/dir.c | 248 +++++++-
fs/ext2/ext2.h | 4 +
fs/ext2/inode.c | 11 +-
fs/ext2/namei.c | 89 +++-
fs/ext2/super.c | 6 +
fs/jffs2/dir.c | 104 ++++-
fs/jffs2/fs.c | 4 +
fs/jffs2/super.c | 2 +-
fs/libfs.c | 21 +-
fs/namei.c | 793 ++++++++++++++++++++++---
fs/namespace.c | 146 +++++-
fs/nfsd/nfs3xdr.c | 5 +
fs/nfsd/nfs4xdr.c | 5 +
fs/nfsd/nfsxdr.c | 4 +
fs/open.c | 116 +++-
fs/readdir.c | 18 +
fs/super.c | 23 +
fs/union.c | 881 ++++++++++++++++++++++++++++
fs/utimes.c | 13 +-
include/linux/dcache.h | 40 ++
include/linux/ext2_fs.h | 5 +
include/linux/fs.h | 16 +
include/linux/jffs2.h | 8 +
include/linux/mount.h | 7 +-
include/linux/namei.h | 2 +
include/linux/union.h | 77 +++
mm/shmem.c | 195 ++++++-
36 files changed, 3483 insertions(+), 160 deletions(-)
create mode 100644 Documentation/filesystems/union-mounts.txt
create mode 100644 fs/union.c
create mode 100644 include/linux/union.h


2010-04-15 23:05:26

by Valerie Aurora

[permalink] [raw]
Subject: [PATCH 02/35] VFS: Add read-only users count to superblock

While we can check if a file system is currently read-only, we can't
guarantee that it will stay read-only. The file system can be
remounted read-write at any time; it's also conceivable that a file
system can be mounted a second time and converted to read-write if the
underlying fs allows it. This is a problem for union mounts, which
require the underlying file system be read-only. Add a read-only
users count and don't allow remounts to change the file system to
read-write or read-write mounts if there are any read-only users.

Signed-off-by: Valerie Aurora <[email protected]>
Cc: Alexander Viro <[email protected]>
---
fs/namespace.c | 11 +++++++++++
fs/super.c | 23 +++++++++++++++++++++++
include/linux/fs.h | 8 ++++++++
3 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 1cd59a0..9a40282 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -200,6 +200,17 @@ int __mnt_is_readonly(struct vfsmount *mnt)
}
EXPORT_SYMBOL_GPL(__mnt_is_readonly);

+static void inc_hard_readonly_users(struct vfsmount *mnt)
+{
+ mnt->mnt_sb->s_hard_readonly_users++;
+}
+
+static void dec_hard_readonly_users(struct vfsmount *mnt)
+{
+ BUG_ON(mnt->mnt_sb->s_hard_readonly_users == 0);
+ mnt->mnt_sb->s_hard_readonly_users--;
+}
+
static inline void inc_mnt_writers(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
diff --git a/fs/super.c b/fs/super.c
index f35ac60..fa9b40b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -117,6 +117,7 @@ out:
*/
static inline void destroy_super(struct super_block *s)
{
+ BUG_ON(s->s_hard_readonly_users);
security_sb_free(s);
kfree(s->s_subtype);
kfree(s->s_options);
@@ -556,6 +557,21 @@ out:
return err;
}

+/*
+ * Some uses of file systems require that they never be mounted
+ * read-write anywhere (e.g., the lower layers of union mounts must
+ * always be read-only). If there are any of these "hard" read-only
+ * mounts, don't permit a transition to read-write.
+ *
+ * Must be called while holding the namespace lock.
+ */
+
+int sb_is_hard_readonly(struct super_block *sb)
+{
+ return sb->s_hard_readonly_users ? 1 : 0;
+}
+EXPORT_SYMBOL(sb_is_hard_readonly);
+
/**
* do_remount_sb - asks filesystem to change mount options.
* @sb: superblock in question
@@ -598,6 +614,9 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
return -EBUSY;
}

+ if (remount_rw && sb_is_hard_readonly(sb))
+ return -EROFS;
+
if (sb->s_op->remount_fs) {
retval = sb->s_op->remount_fs(sb, &flags, data);
if (retval)
@@ -969,6 +988,10 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
"negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);

+ error = -EROFS;
+ if (!(flags & MS_RDONLY) && sb_is_hard_readonly(mnt->mnt_sb))
+ goto out_sb;
+
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
up_write(&mnt->mnt_sb->s_umount);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 10b8ded..234ebc2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1383,6 +1383,13 @@ struct super_block {
* generic_show_options()
*/
char *s_options;
+
+ /*
+ * Some mounts require that the underlying file system never
+ * transition to read-write. They mark the sb itself as
+ * read-only.
+ */
+ int s_hard_readonly_users;
};

extern struct timespec current_fs_time(struct super_block *sb);
@@ -1767,6 +1774,7 @@ extern int get_sb_nodev(struct file_system_type *fs_type,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt);
void generic_shutdown_super(struct super_block *sb);
+int sb_is_hard_readonly(struct super_block *sb);
void kill_block_super(struct super_block *sb);
void kill_anon_super(struct super_block *sb);
void kill_litter_super(struct super_block *sb);
--
1.6.3.3

2010-04-15 23:05:44

by Valerie Aurora

[permalink] [raw]
Subject: [PATCH 01/35] VFS: Make lookup_hash() return a struct path

From: Jan Blunck <[email protected]>

This patch changes lookup_hash() into returning a struct path.

Signed-off-by: Jan Blunck <[email protected]>
Signed-off-by: Valerie Aurora <[email protected]>
Cc: Alexander Viro <[email protected]>
---
fs/namei.c | 113 ++++++++++++++++++++++++++++++-----------------------------
1 files changed, 57 insertions(+), 56 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 981f72c..9013d17 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1155,7 +1155,7 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
}

static struct dentry *__lookup_hash(struct qstr *name,
- struct dentry *base, struct nameidata *nd)
+ struct dentry *base, struct nameidata *nd)
{
struct dentry *dentry;
struct inode *inode;
@@ -1212,14 +1212,22 @@ out:
* needs parent already locked. Doesn't follow mounts.
* SMP-safe.
*/
-static struct dentry *lookup_hash(struct nameidata *nd)
+static int lookup_hash(struct nameidata *nd, struct qstr *name,
+ struct path *path)
{
int err;

err = exec_permission(nd->path.dentry->d_inode);
if (err)
- return ERR_PTR(err);
- return __lookup_hash(&nd->last, nd->path.dentry, nd);
+ return err;
+ path->mnt = nd->path.mnt;
+ path->dentry = __lookup_hash(name, nd->path.dentry, nd);
+ if (IS_ERR(path->dentry)) {
+ err = PTR_ERR(path->dentry);
+ path->dentry = NULL;
+ path->mnt = NULL;
+ }
+ return err;
}

static int __lookup_one_len(const char *name, struct qstr *this,
@@ -1700,12 +1708,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path,

/* OK, it's O_CREAT */
mutex_lock(&dir->d_inode->i_mutex);
+ error = lookup_hash(nd, &nd->last, path);

- path->dentry = lookup_hash(nd);
- path->mnt = nd->path.mnt;
-
- error = PTR_ERR(path->dentry);
- if (IS_ERR(path->dentry)) {
+ if (error) {
mutex_unlock(&dir->d_inode->i_mutex);
goto exit;
}
@@ -1954,7 +1959,8 @@ EXPORT_SYMBOL(filp_open);
*/
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
{
- struct dentry *dentry = ERR_PTR(-EEXIST);
+ struct path path;
+ int err;

mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
/*
@@ -1962,7 +1968,7 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
* (foo/., foo/.., /////)
*/
if (nd->last_type != LAST_NORM)
- goto fail;
+ return ERR_PTR(-EEXIST);
nd->flags &= ~LOOKUP_PARENT;
nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
nd->intent.open.flags = O_EXCL;
@@ -1970,11 +1976,11 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
/*
* Do the final lookup.
*/
- dentry = lookup_hash(nd);
- if (IS_ERR(dentry))
- goto fail;
+ err = lookup_hash(nd, &nd->last, &path);
+ if (err)
+ return ERR_PTR(err);

- if (dentry->d_inode)
+ if (path.dentry->d_inode)
goto eexist;
/*
* Special case - lookup gave negative, but... we had foo/bar/
@@ -1983,15 +1989,14 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
* been asking for (non-existent) directory. -ENOENT for you.
*/
if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
- dput(dentry);
- dentry = ERR_PTR(-ENOENT);
+ dput(path.dentry);
+ return ERR_PTR(-ENOENT);
}
- return dentry;
+
+ return path.dentry;
eexist:
- dput(dentry);
- dentry = ERR_PTR(-EEXIST);
-fail:
- return dentry;
+ path_put_conditional(&path, nd);
+ return ERR_PTR(-EEXIST);
}
EXPORT_SYMBOL_GPL(lookup_create);

@@ -2224,7 +2229,7 @@ static long do_rmdir(int dfd, const char __user *pathname)
{
int error = 0;
char * name;
- struct dentry *dentry;
+ struct path path;
struct nameidata nd;

error = user_path_parent(dfd, pathname, &nd, &name);
@@ -2246,21 +2251,20 @@ static long do_rmdir(int dfd, const char __user *pathname)
nd.flags &= ~LOOKUP_PARENT;

mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
- dentry = lookup_hash(&nd);
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry))
+ error = lookup_hash(&nd, &nd.last, &path);
+ if (error)
goto exit2;
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit3;
- error = security_path_rmdir(&nd.path, dentry);
+ error = security_path_rmdir(&nd.path, path.dentry);
if (error)
goto exit4;
- error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+ error = vfs_rmdir(nd.path.dentry->d_inode, path.dentry);
exit4:
mnt_drop_write(nd.path.mnt);
exit3:
- dput(dentry);
+ path_put_conditional(&path, &nd);
exit2:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
exit1:
@@ -2316,7 +2320,7 @@ static long do_unlinkat(int dfd, const char __user *pathname)
{
int error;
char *name;
- struct dentry *dentry;
+ struct path path;
struct nameidata nd;
struct inode *inode = NULL;

@@ -2331,26 +2335,25 @@ static long do_unlinkat(int dfd, const char __user *pathname)
nd.flags &= ~LOOKUP_PARENT;

mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
- dentry = lookup_hash(&nd);
- error = PTR_ERR(dentry);
- if (!IS_ERR(dentry)) {
+ error = lookup_hash(&nd, &nd.last, &path);
+ if (!error) {
/* Why not before? Because we want correct error value */
if (nd.last.name[nd.last.len])
goto slashes;
- inode = dentry->d_inode;
+ inode = path.dentry->d_inode;
if (inode)
atomic_inc(&inode->i_count);
error = mnt_want_write(nd.path.mnt);
if (error)
goto exit2;
- error = security_path_unlink(&nd.path, dentry);
+ error = security_path_unlink(&nd.path, path.dentry);
if (error)
goto exit3;
- error = vfs_unlink(nd.path.dentry->d_inode, dentry);
+ error = vfs_unlink(nd.path.dentry->d_inode, path.dentry);
exit3:
mnt_drop_write(nd.path.mnt);
exit2:
- dput(dentry);
+ path_put_conditional(&path, &nd);
}
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
if (inode)
@@ -2361,8 +2364,8 @@ exit1:
return error;

slashes:
- error = !dentry->d_inode ? -ENOENT :
- S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
+ error = !path.dentry->d_inode ? -ENOENT :
+ S_ISDIR(path.dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
goto exit2;
}

@@ -2697,7 +2700,7 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname)
{
struct dentry *old_dir, *new_dir;
- struct dentry *old_dentry, *new_dentry;
+ struct path old, new;
struct dentry *trap;
struct nameidata oldnd, newnd;
char *from;
@@ -2731,16 +2734,15 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,

trap = lock_rename(new_dir, old_dir);

- old_dentry = lookup_hash(&oldnd);
- error = PTR_ERR(old_dentry);
- if (IS_ERR(old_dentry))
+ error = lookup_hash(&oldnd, &oldnd.last, &old);
+ if (error)
goto exit3;
/* source must exist */
error = -ENOENT;
- if (!old_dentry->d_inode)
+ if (!old.dentry->d_inode)
goto exit4;
/* unless the source is a directory trailing slashes give -ENOTDIR */
- if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
+ if (!S_ISDIR(old.dentry->d_inode->i_mode)) {
error = -ENOTDIR;
if (oldnd.last.name[oldnd.last.len])
goto exit4;
@@ -2749,32 +2751,31 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
}
/* source should not be ancestor of target */
error = -EINVAL;
- if (old_dentry == trap)
+ if (old.dentry == trap)
goto exit4;
- new_dentry = lookup_hash(&newnd);
- error = PTR_ERR(new_dentry);
- if (IS_ERR(new_dentry))
+ error = lookup_hash(&newnd, &newnd.last, &new);
+ if (error)
goto exit4;
/* target should not be an ancestor of source */
error = -ENOTEMPTY;
- if (new_dentry == trap)
+ if (new.dentry == trap)
goto exit5;

error = mnt_want_write(oldnd.path.mnt);
if (error)
goto exit5;
- error = security_path_rename(&oldnd.path, old_dentry,
- &newnd.path, new_dentry);
+ error = security_path_rename(&oldnd.path, old.dentry,
+ &newnd.path, new.dentry);
if (error)
goto exit6;
- error = vfs_rename(old_dir->d_inode, old_dentry,
- new_dir->d_inode, new_dentry);
+ error = vfs_rename(old_dir->d_inode, old.dentry,
+ new_dir->d_inode, new.dentry);
exit6:
mnt_drop_write(oldnd.path.mnt);
exit5:
- dput(new_dentry);
+ path_put_conditional(&new, &newnd);
exit4:
- dput(old_dentry);
+ path_put_conditional(&old, &oldnd);
exit3:
unlock_rename(new_dir, old_dir);
exit2:
--
1.6.3.3

2010-04-15 23:46:03

by Valerie Aurora

[permalink] [raw]
Subject: [PATCH 03/35] autofs4: Save autofs trigger's vfsmount in super block info

From: Jan Blunck <[email protected]>

(Resend due to kernel.org complaining about XXX in original subject)

XXX - This is broken and included just to make union mounts work. See
discussion at:

http://kerneltrap.org/mailarchive/linux-fsdevel/2010/1/15/6708053/thread

Original commit message:

This is a bugfix/replacement for commit
051d381259eb57d6074d02a6ba6e90e744f1a29f:

During a path walk if an autofs trigger is mounted on a dentry,
when the follow_link method is called, the nameidata struct
contains the vfsmount and mountpoint dentry of the parent mount
while the dentry that is passed in is the root of the autofs
trigger mount. I believe it is impossible to get the vfsmount of
the trigger mount, within the follow_link method, when only the
parent vfsmount and the root dentry of the trigger mount are
known.

The solution in this commit was to replace the path embedded in the
parent's nameidata with the path of the link itself in
__do_follow_link(). This is a relatively harmless misuse of the
field, but union mounts ran into a bug during follow_link() caused by
the nameidata containing the wrong path (we count on it being what it
is all other places - the path of the parent).

A cleaner and easier to understand solution is to save the necessary
vfsmount in the autofs superblock info when it is mounted. Then we
can easily update the vfsmount in autofs4_follow_link().

Signed-off-by: Jan Blunck <[email protected]>
Signed-off-by: Valerie Aurora <[email protected]>
Acked-by: Ian Kent <[email protected]>
Cc: [email protected]
Cc: Alexander Viro <[email protected]>
---
fs/autofs4/autofs_i.h | 1 +
fs/autofs4/init.c | 11 ++++++++++-
fs/autofs4/root.c | 6 ++++++
fs/namei.c | 7 ++-----
4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 3d283ab..de3af64 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -133,6 +133,7 @@ struct autofs_sb_info {
int reghost_enabled;
int needs_reghost;
struct super_block *sb;
+ struct vfsmount *mnt;
struct mutex wq_mutex;
spinlock_t fs_lock;
struct autofs_wait_queue *queues; /* Wait queue pointer */
diff --git a/fs/autofs4/init.c b/fs/autofs4/init.c
index 9722e4b..5e0dcd7 100644
--- a/fs/autofs4/init.c
+++ b/fs/autofs4/init.c
@@ -17,7 +17,16 @@
static int autofs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
- return get_sb_nodev(fs_type, flags, data, autofs4_fill_super, mnt);
+ struct autofs_sb_info *sbi;
+ int ret;
+
+ ret = get_sb_nodev(fs_type, flags, data, autofs4_fill_super, mnt);
+ if (ret)
+ return ret;
+
+ sbi = autofs4_sbi(mnt->mnt_sb);
+ sbi->mnt = mnt;
+ return 0;
}

static struct file_system_type autofs_fs_type = {
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index a015b49..267fe6d 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -219,6 +219,12 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
nd->flags);
+
+ dput(nd->path.dentry);
+ mntput(nd->path.mnt);
+ nd->path.mnt = mntget(sbi->mnt);
+ nd->path.dentry = dget(dentry);
+
/*
* For an expire of a covered direct or offset mount we need
* to break out of follow_down() at the autofs mount trigger
diff --git a/fs/namei.c b/fs/namei.c
index 9013d17..8e4c75f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -538,11 +538,8 @@ __do_follow_link(struct path *path, struct nameidata *nd, void **p)
touch_atime(path->mnt, dentry);
nd_set_link(nd, NULL);

- if (path->mnt != nd->path.mnt) {
- path_to_nameidata(path, nd);
- dget(dentry);
- }
- mntget(path->mnt);
+ if (path->mnt == nd->path.mnt)
+ mntget(nd->path.mnt);
nd->last_type = LAST_BIND;
*p = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(*p);
--
1.6.3.3

2010-04-21 22:07:05

by Randy Dunlap

[permalink] [raw]
Subject: Re: [PATCH 00/35] Union mounts - everything but the xattrs

On Thu, 15 Apr 2010 16:04:07 -0700 Valerie Aurora wrote:

> This patch series implements union mounts for every system call
> except:
>
> - xattr-related calls
> - fchmod()/fchown()/futimensat() on an fd
>
> The copyup portion is a proof of concept based around union_path_nd(),
> which looks up both the target <mnt,dentry> pair and its parent's. If
> the parent is on a union mount, and the target is on a lower layer, we
> copy up the target.
>
> This patch set is very raw and could use even the most superficial
> review. Just take a look at Erez's review from December to see how
> low-hanging the fruit is on this one.
>
> -VAL


Hi VAL,

In the future, please make patches 1-N reply/refer to patch 0 instead of to
the preceding numbered patch.


thanks,
---
~Randy

2010-04-21 23:35:41

by Valerie Aurora

[permalink] [raw]
Subject: Re: [PATCH 00/35] Union mounts - everything but the xattrs

On Wed, Apr 21, 2010 at 03:06:34PM -0700, Randy Dunlap wrote:
> On Thu, 15 Apr 2010 16:04:07 -0700 Valerie Aurora wrote:
>
> > This patch series implements union mounts for every system call
> > except:
> >
> > - xattr-related calls
> > - fchmod()/fchown()/futimensat() on an fd
> >
> > The copyup portion is a proof of concept based around union_path_nd(),
> > which looks up both the target <mnt,dentry> pair and its parent's. If
> > the parent is on a union mount, and the target is on a lower layer, we
> > copy up the target.
> >
> > This patch set is very raw and could use even the most superficial
> > review. Just take a look at Erez's review from December to see how
> > low-hanging the fruit is on this one.
> >
> > -VAL
>
>
> Hi VAL,
>
> In the future, please make patches 1-N reply/refer to patch 0 instead of to
> the preceding numbered patch.

Okay.

-VAL