From: Trond Myklebust Date: Wed, 31 Jan 2007 08:16:24 -0500 NFS: Dont clobber more uptodate values in nfs_set_verifier() nfs_lookup_revalidate and friends are not serialised, so it is currently quite possible for the dentry to be revalidated, and then have the updated verifier replaced with an older value by another process. Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 19 ++++++++++++++----- 1 files changed, 14 insertions(+), 5 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 062e108..37c1dd6 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -637,7 +637,7 @@ int nfs_fsync_dir(struct file *filp, str * In the case it has, we assume that the dentries are untrustworthy * and may need to be looked up again. */ -static inline int nfs_check_verifier(struct inode *dir, struct dentry *dentry) +static int nfs_check_verifier(struct inode *dir, struct dentry *dentry) { if (IS_ROOT(dentry)) return 1; @@ -652,6 +652,12 @@ static inline void nfs_set_verifier(stru dentry->d_fsdata = (void *)verf; } +static void nfs_refresh_verifier(struct dentry * dentry, unsigned long verf) +{ + if (time_after(verf, (unsigned long)dentry->d_fsdata)) + nfs_set_verifier(dentry, verf); +} + /* * Whenever an NFS operation succeeds, we know that the dentry * is valid, so we update the revalidation timestamp. @@ -785,7 +791,7 @@ static int nfs_lookup_revalidate(struct goto out_bad; nfs_renew_times(dentry); - nfs_set_verifier(dentry, verifier); + nfs_refresh_verifier(dentry, verifier); out_valid: unlock_kernel(); dput(parent); @@ -1085,7 +1091,7 @@ static int nfs_open_revalidate(struct de verifier = nfs_save_change_attribute(dir); ret = nfs4_open_revalidate(dir, dentry, openflags, nd); if (!ret) - nfs_set_verifier(dentry, verifier); + nfs_refresh_verifier(dentry, verifier); unlock_kernel(); out: dput(parent); @@ -1159,10 +1165,13 @@ static struct dentry *nfs_readdir_lookup dentry = alias; } -out_renew: nfs_renew_times(dentry); nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); return dentry; +out_renew: + nfs_renew_times(dentry); + nfs_refresh_verifier(dentry, nfs_save_change_attribute(dir)); + return dentry; } /* @@ -1700,7 +1709,7 @@ out: if (!error) { d_move(old_dentry, new_dentry); nfs_renew_times(new_dentry); - nfs_set_verifier(new_dentry, nfs_save_change_attribute(new_dir)); + nfs_refresh_verifier(new_dentry, nfs_save_change_attribute(new_dir)); } /* new dentry created? */