NFS: Avoid duplicate uncached readdir calls on eof

[ Upstream commit e1d2699b96793d19388e302fa095e0da2c145701 ]

If we've reached the end of the directory, then cache that information
in the context so that we don't need to do an uncached readdir in order
to rediscover that fact.

Fixes: 794092c57f89 ("NFS: Do uncached readdir when we're seeking a cookie in an empty page cache")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 63d7da0b7e32cbed84c957b01dd33a92bdcfbf09..b2460a0504411fad843c97627a8ffd7d624d1377 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -79,6 +79,7 @@ static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir
                ctx->dir_cookie = 0;
                ctx->dup_cookie = 0;
                ctx->page_index = 0;
+               ctx->eof = false;
                spin_lock(&dir->i_lock);
                if (list_empty(&nfsi->open_files) &&
                    (nfsi->cache_validity & NFS_INO_DATA_INVAL_DEFER))
@@ -167,6 +168,7 @@ struct nfs_readdir_descriptor {
        unsigned int    cache_entry_index;
        signed char duped;
        bool plus;
+       bool eob;
        bool eof;
 };
 
@@ -988,7 +990,7 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
                ent = &array->array[i];
                if (!dir_emit(desc->ctx, ent->name, ent->name_len,
                    nfs_compat_user_ino64(ent->ino), ent->d_type)) {
-                       desc->eof = true;
+                       desc->eob = true;
                        break;
                }
                memcpy(desc->verf, verf, sizeof(desc->verf));
@@ -1004,7 +1006,7 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
                        desc->duped = 1;
        }
        if (array->page_is_eof)
-               desc->eof = true;
+               desc->eof = !desc->eob;
 
        kunmap(desc->page);
        dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %llu\n",
@@ -1047,7 +1049,7 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc)
 
        status = nfs_readdir_xdr_to_array(desc, desc->verf, verf, arrays, sz);
 
-       for (i = 0; !desc->eof && i < sz && arrays[i]; i++) {
+       for (i = 0; !desc->eob && i < sz && arrays[i]; i++) {
                desc->page = arrays[i];
                nfs_do_filldir(desc, verf);
        }
@@ -1106,9 +1108,15 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
        desc->duped = dir_ctx->duped;
        page_index = dir_ctx->page_index;
        desc->attr_gencount = dir_ctx->attr_gencount;
+       desc->eof = dir_ctx->eof;
        memcpy(desc->verf, dir_ctx->verf, sizeof(desc->verf));
        spin_unlock(&file->f_lock);
 
+       if (desc->eof) {
+               res = 0;
+               goto out_free;
+       }
+
        if (test_and_clear_bit(NFS_INO_FORCE_READDIR, &nfsi->flags) &&
            list_is_singular(&nfsi->open_files))
                invalidate_mapping_pages(inode->i_mapping, page_index + 1, -1);
@@ -1142,7 +1150,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
 
                nfs_do_filldir(desc, nfsi->cookieverf);
                nfs_readdir_page_unlock_and_put_cached(desc);
-       } while (!desc->eof);
+       } while (!desc->eob && !desc->eof);
 
        spin_lock(&file->f_lock);
        dir_ctx->dir_cookie = desc->dir_cookie;
@@ -1150,9 +1158,10 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
        dir_ctx->duped = desc->duped;
        dir_ctx->attr_gencount = desc->attr_gencount;
        dir_ctx->page_index = desc->page_index;
+       dir_ctx->eof = desc->eof;
        memcpy(dir_ctx->verf, desc->verf, sizeof(dir_ctx->verf));
        spin_unlock(&file->f_lock);
-
+out_free:
        kfree(desc);
 
 out:
@@ -1194,6 +1203,7 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
                if (offset == 0)
                        memset(dir_ctx->verf, 0, sizeof(dir_ctx->verf));
                dir_ctx->duped = 0;
+               dir_ctx->eof = false;
        }
        spin_unlock(&filp->f_lock);
        return offset;

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index f33559acbcc283aa34a2f40e183216f31b633bde..29a2ab5de1daac3db737368a8c3a0913a4ff315c 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -105,6 +105,7 @@ struct nfs_open_dir_context {
        __u64 dup_cookie;
        pgoff_t page_index;
        signed char duped;
+       bool eof;
 };
 
 /*