[PATCH v4 03/21] NFS: Ensure contents of struct nfs_open_dir_context are consistent

trondmy
2020-11-07T14:13:40Z

Ensure that the contents of struct nfs_open_dir_context are consistent
by setting them under the file->f_lock from a private copy (that is
known to be consistent).

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
fs/nfs/dir.c | 72 +++++++++++++++++++++++++++++++---------------------
1 file changed, 43 insertions(+), 29 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 4e011adaf967..67d8595cd6e5 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -144,20 +144,23 @@ struct nfs_cache_array {
struct nfs_cache_array_entry array[];
};

-typedef struct {
+typedef struct nfs_readdir_descriptor {
struct file *file;
struct page *page;
struct dir_context *ctx;
unsigned long page_index;
- u64 *dir_cookie;
+ u64 dir_cookie;
u64 last_cookie;
+ u64 dup_cookie;
loff_t current_index;
loff_t prev_index;

unsigned long dir_verifier;
unsigned long timestamp;
unsigned long gencount;
+ unsigned long attr_gencount;
unsigned int cache_entry_index;
+ signed char duped;
bool plus;
bool eof;
} nfs_readdir_descriptor_t;
@@ -273,7 +276,7 @@ int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descri
}

index = (unsigned int)diff;
- *desc->dir_cookie = array->array[index].cookie;
+ desc->dir_cookie = array->array[index].cookie;
desc->cache_entry_index = index;
return 0;
out_eof:
@@ -298,33 +301,32 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
int status = -EAGAIN;

for (i = 0; i < array->size; i++) {
- if (array->array[i].cookie == *desc->dir_cookie) {
+ if (array->array[i].cookie == desc->dir_cookie) {
struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
- struct nfs_open_dir_context *ctx = desc->file->private_data;

new_pos = desc->current_index + i;
- if (ctx->attr_gencount != nfsi->attr_gencount ||
+ if (desc->attr_gencount != nfsi->attr_gencount ||
!nfs_readdir_inode_mapping_valid(nfsi)) {
- ctx->duped = 0;
- ctx->attr_gencount = nfsi->attr_gencount;
+ desc->duped = 0;
+ desc->attr_gencount = nfsi->attr_gencount;
} else if (new_pos < desc->prev_index) {
- if (ctx->duped > 0
- && ctx->dup_cookie == *desc->dir_cookie) {
+ if (desc->duped > 0
+ && desc->dup_cookie == desc->dir_cookie) {
if (printk_ratelimit()) {
pr_notice("NFS: directory %pD2 contains a readdir loop."
"Please contact your server vendor. "
"The file: %.*s has duplicate cookie %llu\n",
desc->file, array->array[i].string.len,
- array->array[i].string.name, *desc->dir_cookie);
+ array->array[i].string.name, desc->dir_cookie);
}
status = -ELOOP;
goto out;
}
- ctx->dup_cookie = *desc->dir_cookie;
- ctx->duped = -1;
+ desc->dup_cookie = desc->dir_cookie;
+ desc->duped = -1;
}
if (nfs_readdir_use_cookie(desc->file))
- desc->ctx->pos = *desc->dir_cookie;
+ desc->ctx->pos = desc->dir_cookie;
else
desc->ctx->pos = new_pos;
desc->prev_index = new_pos;
@@ -334,7 +336,7 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
}
if (array->eof_index >= 0) {
status = -EBADCOOKIE;
- if (*desc->dir_cookie == array->last_cookie)
+ if (desc->dir_cookie == array->last_cookie)
desc->eof = true;
}
out:
@@ -349,7 +351,7 @@ int nfs_readdir_search_array(nfs_readdir_descriptor_t *desc)

array = kmap(desc->page);

- if (*desc->dir_cookie == 0)
+ if (desc->dir_cookie == 0)
status = nfs_readdir_search_for_pos(array, desc);
else
status = nfs_readdir_search_for_cookie(array, desc);
@@ -801,7 +803,6 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
int i = 0;
int res = 0;
struct nfs_cache_array *array = NULL;
- struct nfs_open_dir_context *ctx = file->private_data;

array = kmap(desc->page);
for (i = desc->cache_entry_index; i < array->size; i++) {
@@ -814,22 +815,22 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
break;
}
if (i < (array->size-1))
- *desc->dir_cookie = array->array[i+1].cookie;
+ desc->dir_cookie = array->array[i+1].cookie;
else
- *desc->dir_cookie = array->last_cookie;
+ desc->dir_cookie = array->last_cookie;
if (nfs_readdir_use_cookie(file))
- desc->ctx->pos = *desc->dir_cookie;
+ desc->ctx->pos = desc->dir_cookie;
else
desc->ctx->pos++;
- if (ctx->duped != 0)
- ctx->duped = 1;
+ if (desc->duped != 0)
+ desc->duped = 1;
}
if (array->eof_index >= 0)
desc->eof = true;

kunmap(desc->page);
dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n",
- (unsigned long long)*desc->dir_cookie, res);
+ (unsigned long long)desc->dir_cookie, res);
return res;
}

@@ -851,10 +852,9 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc)
struct page *page = NULL;
int status;
struct inode *inode = file_inode(desc->file);
- struct nfs_open_dir_context *ctx = desc->file->private_data;

dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
- (unsigned long long)*desc->dir_cookie);
+ (unsigned long long)desc->dir_cookie);

page = alloc_page(GFP_HIGHUSER);
if (!page) {
@@ -863,9 +863,9 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc)
}

desc->page_index = 0;
- desc->last_cookie = *desc->dir_cookie;
+ desc->last_cookie = desc->dir_cookie;
desc->page = page;
- ctx->duped = 0;
+ desc->duped = 0;

status = nfs_readdir_xdr_to_array(desc, page, inode);
if (status < 0)
@@ -894,7 +894,6 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
nfs_readdir_descriptor_t my_desc = {
.file = file,
.ctx = ctx,
- .dir_cookie = &dir_ctx->dir_cookie,
.plus = nfs_use_readdirplus(inode, ctx),
},
*desc = &my_desc;
@@ -915,13 +914,20 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
if (res < 0)
goto out;

+ spin_lock(&file->f_lock);
+ desc->dir_cookie = dir_ctx->dir_cookie;
+ desc->dup_cookie = dir_ctx->dup_cookie;
+ desc->duped = dir_ctx->duped;
+ desc->attr_gencount = dir_ctx->attr_gencount;
+ spin_unlock(&file->f_lock);
+
do {
res = readdir_search_pagecache(desc);

if (res == -EBADCOOKIE) {
res = 0;
/* This means either end of directory */
- if (*desc->dir_cookie && !desc->eof) {
+ if (desc->dir_cookie && !desc->eof) {
/* Or that the server has 'lost' a cookie */
res = uncached_readdir(desc);
if (res == 0)
@@ -946,6 +952,14 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
if (res < 0)
break;
} while (!desc->eof);
+
+ spin_lock(&file->f_lock);
+ dir_ctx->dir_cookie = desc->dir_cookie;
+ dir_ctx->dup_cookie = desc->dup_cookie;
+ dir_ctx->duped = desc->duped;
+ dir_ctx->attr_gencount = desc->attr_gencount;
+ spin_unlock(&file->f_lock);
+
out:
if (res > 0)
res = 0;
--
2.28.0