Commit 668609dc authored by Trond Myklebust's avatar Trond Myklebust Committed by Linus Torvalds

[PATCH] Support for cached lookups via readdirplus [4/6]

Add support for positive lookups using the READDIRPLUS cached
information. Both new lookups and lookup revalidation is supported.

Use READDIRPLUS instead of READDIR on NFSv3 directories with lengths
shorter than 8*PAGE_SIZE.

Note that inode attribute information is only updated if it is seen to
be more recent than any existing cached information.
parent c385d3e1
...@@ -37,6 +37,8 @@ ...@@ -37,6 +37,8 @@
static int nfs_readdir(struct file *, void *, filldir_t); static int nfs_readdir(struct file *, void *, filldir_t);
static struct dentry *nfs_lookup(struct inode *, struct dentry *); static struct dentry *nfs_lookup(struct inode *, struct dentry *);
static int nfs_cached_lookup(struct inode *, struct dentry *,
struct nfs_fh *, struct nfs_fattr *);
static int nfs_create(struct inode *, struct dentry *, int); static int nfs_create(struct inode *, struct dentry *, int);
static int nfs_mkdir(struct inode *, struct dentry *, int); static int nfs_mkdir(struct inode *, struct dentry *, int);
static int nfs_rmdir(struct inode *, struct dentry *); static int nfs_rmdir(struct inode *, struct dentry *);
...@@ -504,6 +506,15 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags) ...@@ -504,6 +506,15 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
goto out_valid; goto out_valid;
} }
error = nfs_cached_lookup(dir, dentry, &fhandle, &fattr);
if (!error) {
if (memcmp(NFS_FH(inode), &fhandle, sizeof(struct nfs_fh))!= 0)
goto out_bad;
if (nfs_lookup_verify_inode(inode))
goto out_bad;
goto out_valid_renew;
}
if (NFS_STALE(inode)) if (NFS_STALE(inode))
goto out_bad; goto out_bad;
...@@ -515,6 +526,7 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags) ...@@ -515,6 +526,7 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
if ((error = nfs_refresh_inode(inode, &fattr)) != 0) if ((error = nfs_refresh_inode(inode, &fattr)) != 0)
goto out_bad; goto out_bad;
out_valid_renew:
nfs_renew_times(dentry); nfs_renew_times(dentry);
out_valid: out_valid:
unlock_kernel(); unlock_kernel();
...@@ -578,7 +590,7 @@ struct dentry_operations nfs_dentry_operations = { ...@@ -578,7 +590,7 @@ struct dentry_operations nfs_dentry_operations = {
static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry) static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry)
{ {
struct inode *inode; struct inode *inode = NULL;
int error; int error;
struct nfs_fh fhandle; struct nfs_fh fhandle;
struct nfs_fattr fattr; struct nfs_fattr fattr;
...@@ -594,8 +606,19 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry) ...@@ -594,8 +606,19 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry)
dentry->d_op = &nfs_dentry_operations; dentry->d_op = &nfs_dentry_operations;
lock_kernel(); lock_kernel();
error = nfs_cached_lookup(dir, dentry, &fhandle, &fattr);
if (!error) {
error = -EACCES;
inode = nfs_fhget(dentry, &fhandle, &fattr);
if (inode) {
d_add(dentry, inode);
nfs_renew_times(dentry);
error = 0;
}
goto out;
}
error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr); error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr);
inode = NULL;
if (error == -ENOENT) if (error == -ENOENT)
goto no_entry; goto no_entry;
if (!error) { if (!error) {
...@@ -613,6 +636,79 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry) ...@@ -613,6 +636,79 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry)
return ERR_PTR(error); return ERR_PTR(error);
} }
static inline
int find_dirent_name(nfs_readdir_descriptor_t *desc, struct page *page, struct dentry *dentry)
{
struct nfs_entry *entry = desc->entry;
int status;
while((status = dir_decode(desc)) == 0) {
if (entry->len != dentry->d_name.len)
continue;
if (memcmp(entry->name, dentry->d_name.name, entry->len))
continue;
if (!(entry->fattr->valid & NFS_ATTR_FATTR))
continue;
break;
}
return status;
}
/*
* Use the cached Readdirplus results in order to avoid a LOOKUP call
* whenever we believe that the parent directory has not changed.
*
* We assume that any file creation/rename changes the directory mtime.
* As this results in a page cache invalidation whenever it occurs,
* we don't require any other tests for cache coherency.
*/
static
int nfs_cached_lookup(struct inode *dir, struct dentry *dentry,
struct nfs_fh *fh, struct nfs_fattr *fattr)
{
nfs_readdir_descriptor_t desc;
struct nfs_server *server;
struct nfs_entry entry;
struct page *page;
unsigned long timestamp = NFS_MTIME_UPDATE(dir);
int res;
if (!NFS_USE_READDIRPLUS(dir))
return -ENOENT;
server = NFS_SERVER(dir);
if (server->flags & NFS_MOUNT_NOAC)
return -ENOENT;
nfs_revalidate_inode(server, dir);
entry.fh = fh;
entry.fattr = fattr;
desc.decode = NFS_PROTO(dir)->decode_dirent;
desc.entry = &entry;
desc.page_index = 0;
desc.plus = 1;
for(;(page = find_get_page(&dir->i_data, desc.page_index)); desc.page_index++) {
res = -EIO;
if (PageUptodate(page)) {
desc.ptr = kmap(page);
res = find_dirent_name(&desc, page, dentry);
kunmap(page);
}
page_cache_release(page);
if (res == 0)
goto out_found;
if (res != -EAGAIN)
break;
}
return -ENOENT;
out_found:
fattr->timestamp = timestamp;
return 0;
}
/* /*
* Code common to create, mkdir, and mknod. * Code common to create, mkdir, and mknod.
*/ */
......
...@@ -644,6 +644,9 @@ nfs_fhget(struct dentry *dentry, struct nfs_fh *fhandle, ...@@ -644,6 +644,9 @@ nfs_fhget(struct dentry *dentry, struct nfs_fh *fhandle,
return __nfs_fhget(sb, fhandle, fattr); return __nfs_fhget(sb, fhandle, fattr);
} }
/* Don't use READDIRPLUS on directories that we believe are too large */
#define NFS_LIMIT_READDIRPLUS (8*PAGE_SIZE)
/* /*
* Look up the inode by super block and fattr->fileid. * Look up the inode by super block and fattr->fileid.
*/ */
...@@ -692,6 +695,9 @@ __nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr) ...@@ -692,6 +695,9 @@ __nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
} else if (S_ISDIR(inode->i_mode)) { } else if (S_ISDIR(inode->i_mode)) {
inode->i_op = &nfs_dir_inode_operations; inode->i_op = &nfs_dir_inode_operations;
inode->i_fop = &nfs_dir_operations; inode->i_fop = &nfs_dir_operations;
if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS)
&& fattr->size <= NFS_LIMIT_READDIRPLUS)
NFS_FLAGS(inode) |= NFS_INO_ADVISE_RDPLUS;
} else if (S_ISLNK(inode->i_mode)) } else if (S_ISLNK(inode->i_mode))
inode->i_op = &nfs_symlink_inode_operations; inode->i_op = &nfs_symlink_inode_operations;
else else
......
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