From 4eec952e42314b53e48fef1f54dd89cbf9789734 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 15 Jul 2008 17:58:13 -0400 Subject: NFS: Add options for finer control of the lookup cache Add the flag NFS_MOUNT_LOOKUP_CACHE_NONEG to turn off the caching of negative dentries. In reality what we do is to force nfs_lookup_revalidate() to always discard negative dentries. Add the flag NFS_MOUNT_LOOKUP_CACHE_NONE for enforcing stricter revalidation of dentries. It forces the revalidate code to always do a lookup instead of just checking the cached mtime of the parent directory. Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/nfs/dir.c') diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 74f92b717f78..49d565412827 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -667,6 +667,8 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry) { if (IS_ROOT(dentry)) return 1; + if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE) + return 0; if (!nfs_verify_change_attribute(dir, dentry->d_time)) return 0; /* Revalidate nfsi->cache_change_attribute before we declare a match */ @@ -750,6 +752,8 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry, /* Don't revalidate a negative dentry if we're creating a new file */ if (nd != NULL && nfs_lookup_check_intent(nd, LOOKUP_CREATE) != 0) return 0; + if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) + return 1; return !nfs_check_verifier(dir, dentry); } -- cgit v1.2.2 From 4704f0e274829e3af00737d2d9adace2d71a9605 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 14 Oct 2008 19:16:07 -0400 Subject: NFS: Fix the resolution problem with nfs_inode_attrs_need_update() It appears that 'jiffies' timestamps do not have high enough resolution for nfs_inode_attrs_need_update(). One problem is that a GETATTR can be launched within < 1 jiffy of the last operation that updated the attribute. Another problem is that RPC calls can take < 1 jiffy to execute. We can fix this by switching the variables to use a simple global counter that gets incremented every time we start another GETATTR call. Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'fs/nfs/dir.c') diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 49d565412827..4807074ada8c 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -156,6 +156,7 @@ typedef struct { decode_dirent_t decode; int plus; unsigned long timestamp; + unsigned long gencount; int timestamp_valid; } nfs_readdir_descriptor_t; @@ -177,7 +178,7 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page *page) struct file *file = desc->file; struct inode *inode = file->f_path.dentry->d_inode; struct rpc_cred *cred = nfs_file_cred(file); - unsigned long timestamp; + unsigned long timestamp, gencount; int error; dfprintk(DIRCACHE, "NFS: %s: reading cookie %Lu into page %lu\n", @@ -186,6 +187,7 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page *page) again: timestamp = jiffies; + gencount = nfs_inc_attr_generation_counter(); error = NFS_PROTO(inode)->readdir(file->f_path.dentry, cred, desc->entry->cookie, page, NFS_SERVER(inode)->dtsize, desc->plus); if (error < 0) { @@ -199,6 +201,7 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page *page) goto error; } desc->timestamp = timestamp; + desc->gencount = gencount; desc->timestamp_valid = 1; SetPageUptodate(page); /* Ensure consistent page alignment of the data. @@ -224,9 +227,10 @@ int dir_decode(nfs_readdir_descriptor_t *desc) if (IS_ERR(p)) return PTR_ERR(p); desc->ptr = p; - if (desc->timestamp_valid) + if (desc->timestamp_valid) { desc->entry->fattr->time_start = desc->timestamp; - else + desc->entry->fattr->gencount = desc->gencount; + } else desc->entry->fattr->valid &= ~NFS_ATTR_FATTR; return 0; } @@ -471,7 +475,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent, struct rpc_cred *cred = nfs_file_cred(file); struct page *page = NULL; int status; - unsigned long timestamp; + unsigned long timestamp, gencount; dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n", (unsigned long long)*desc->dir_cookie); @@ -482,6 +486,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent, goto out; } timestamp = jiffies; + gencount = nfs_inc_attr_generation_counter(); status = NFS_PROTO(inode)->readdir(file->f_path.dentry, cred, *desc->dir_cookie, page, NFS_SERVER(inode)->dtsize, @@ -490,6 +495,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent, desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */ if (status >= 0) { desc->timestamp = timestamp; + desc->gencount = gencount; desc->timestamp_valid = 1; if ((status = dir_decode(desc)) == 0) desc->entry->prev_cookie = *desc->dir_cookie; -- cgit v1.2.2 From 011935a0a710c20bb7ae63523b78856848db1926 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 14 Oct 2008 19:24:50 -0400 Subject: NFS: Fix a resolution problem with nfs_inode->cache_change_attribute The cache_change_attribute is used to decide whether or not a directory has changed, in which case we may need to look it up again. Again, the use of 'jiffies' leads to an issue of resolution. Once again, the fix is to change nfs_inode->cache_change_attribute, and just make it a simple counter. Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/nfs/dir.c') diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 4807074ada8c..2ab70d46ecbc 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -661,7 +661,7 @@ static int nfs_fsync_dir(struct file *filp, struct dentry *dentry, int datasync) */ void nfs_force_lookup_revalidate(struct inode *dir) { - NFS_I(dir)->cache_change_attribute = jiffies; + NFS_I(dir)->cache_change_attribute++; } /* -- cgit v1.2.2