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Allow d_manage() to be used in RCU-walk mode

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Allow d_manage() to be called from pathwalk when it is in RCU-walk mode as well
as when it is in Ref-walk mode.  This permits __follow_mount_rcu() to call
d_manage() directly.  d_manage() needs a parameter to indicate that it is in
RCU-walk mode as it isn't allowed to sleep if in that mode (but should return
-ECHILD instead).

autofs4_d_manage() can then be set to retain RCU-walk mode if the daemon
accesses it and otherwise request dropping back to ref-walk mode.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells
2011-01-14 18:46:51 +00:00
committed by Al Viro
parent 87556ef199
commit ab90911ff9
5 changed files with 22 additions and 12 deletions
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15
fs/namei.c
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@@ -987,7 +987,8 @@ static int follow_managed(struct path *path, unsigned flags)
if (managed & DCACHE_MANAGE_TRANSIT) {
BUG_ON(!path->dentry->d_op);
BUG_ON(!path->dentry->d_op->d_manage);
ret = path->dentry->d_op->d_manage(path->dentry, false);
ret = path->dentry->d_op->d_manage(path->dentry,
false, false);
if (ret < 0)
return ret == -EISDIR ? 0 : ret;
}
@@ -1048,13 +1049,12 @@ int follow_down_one(struct path *path)
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
struct inode **inode, bool reverse_transit)
{
unsigned abort_mask =
reverse_transit ? 0 : DCACHE_MANAGE_TRANSIT;
while (d_mountpoint(path->dentry)) {
struct vfsmount *mounted;
if (path->dentry->d_flags & abort_mask)
return true;
if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) &&
!reverse_transit &&
path->dentry->d_op->d_manage(path->dentry, false, true) < 0)
return false;
mounted = __lookup_mnt(path->mnt, path->dentry, 1);
if (!mounted)
break;
@@ -1132,7 +1132,8 @@ int follow_down(struct path *path, bool mounting_here)
if (managed & DCACHE_MANAGE_TRANSIT) {
BUG_ON(!path->dentry->d_op);
BUG_ON(!path->dentry->d_op->d_manage);
ret = path->dentry->d_op->d_manage(path->dentry, mounting_here);
ret = path->dentry->d_op->d_manage(
path->dentry, mounting_here, false);
if (ret < 0)
return ret == -EISDIR ? 0 : ret;
}