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| author | Ian Kent <raven@themaw.net> | 2011-03-25 01:51:02 +0800 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-03-24 14:24:32 -0400 |
| commit | 62a7375e5d77d654695297c4b39d5d740d901184 (patch) | |
| tree | b479c60a43f22e3bb99d9ebf1af89de2a7020673 | |
| parent | b81a618dcd3ea99de292dbe624f41ca68f464376 (diff) | |
| download | linux-3.10-62a7375e5d77d654695297c4b39d5d740d901184.tar.gz linux-3.10-62a7375e5d77d654695297c4b39d5d740d901184.tar.bz2 linux-3.10-62a7375e5d77d654695297c4b39d5d740d901184.zip | |
vfs - check non-mountpoint dentry might block in __follow_mount_rcu()
When following a mount in rcu-walk mode we must check if the incoming dentry
is telling us it may need to block, even if it isn't actually a mountpoint.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/namei.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/fs/namei.c b/fs/namei.c index d0066e17d45..3cb616d38d9 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -992,6 +992,12 @@ int follow_down_one(struct path *path) return 0; } +static inline bool managed_dentry_might_block(struct dentry *dentry) +{ + return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && + dentry->d_op->d_manage(dentry, true) < 0); +} + /* * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we * meet a managed dentry and we're not walking to "..". True is returned to @@ -1000,19 +1006,26 @@ int follow_down_one(struct path *path) static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, struct inode **inode, bool reverse_transit) { - while (d_mountpoint(path->dentry)) { + for (;;) { struct vfsmount *mounted; - if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) && - !reverse_transit && - path->dentry->d_op->d_manage(path->dentry, true) < 0) + /* + * Don't forget we might have a non-mountpoint managed dentry + * that wants to block transit. + */ + *inode = path->dentry->d_inode; + if (!reverse_transit && + unlikely(managed_dentry_might_block(path->dentry))) return false; + + if (!d_mountpoint(path->dentry)) + break; + mounted = __lookup_mnt(path->mnt, path->dentry, 1); if (!mounted) break; path->mnt = mounted; path->dentry = mounted->mnt_root; nd->seq = read_seqcount_begin(&path->dentry->d_seq); - *inode = path->dentry->d_inode; } if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) |