@@ -2951,12 +2951,14 @@ static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, co
return NULL;
}
-static u64 nfs_access_login_time(const struct task_struct *task,
- const struct cred *cred)
+static inline
+bool nfs_check_access_stale(const struct task_struct *task,
+ const struct cred *cred,
+ const struct nfs_access_entry *cache)
{
const struct task_struct *parent;
const struct cred *pcred;
- u64 ret;
+ u64 login_time;
rcu_read_lock();
for (;;) {
@@ -2966,15 +2968,15 @@ static u64 nfs_access_login_time(const struct task_struct *task,
break;
task = parent;
}
- ret = task->start_time;
+ login_time = task->start_time;
rcu_read_unlock();
- return ret;
+
+ return ((s64)(login_time - cache->timestamp) > 0);
}
static int nfs_access_get_cached_locked(struct inode *inode, const struct cred *cred, u32 *mask, bool may_block)
{
struct nfs_inode *nfsi = NFS_I(inode);
- u64 login_time = nfs_access_login_time(current, cred);
struct nfs_access_entry *cache;
bool retry = true;
int err;
@@ -3003,7 +3005,8 @@ static int nfs_access_get_cached_locked(struct inode *inode, const struct cred *
retry = false;
}
err = -ENOENT;
- if ((s64)(login_time - cache->timestamp) > 0)
+ if ((NFS_SERVER(inode)->flags & NFS_MOUNT_FASC) &&
+ nfs_check_access_stale(current, cred, cache))
goto out;
*mask = cache->mask;
list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
@@ -3023,7 +3026,6 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
* but do it without locking.
*/
struct nfs_inode *nfsi = NFS_I(inode);
- u64 login_time = nfs_access_login_time(current, cred);
struct nfs_access_entry *cache;
int err = -ECHILD;
struct list_head *lh;
@@ -3038,7 +3040,8 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
cache = NULL;
if (cache == NULL)
goto out;
- if ((s64)(login_time - cache->timestamp) > 0)
+ if ((NFS_SERVER(inode)->flags & NFS_MOUNT_FASC) &&
+ nfs_check_access_stale(current, cred, cache))
goto out;
if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
goto out;
@@ -92,6 +92,7 @@ enum nfs_param {
Opt_wsize,
Opt_write,
Opt_xprtsec,
+ Opt_fasc,
};
enum {
@@ -199,6 +200,7 @@ static const struct fs_parameter_spec nfs_fs_parameters[] = {
fsparam_enum ("write", Opt_write, nfs_param_enums_write),
fsparam_u32 ("wsize", Opt_wsize),
fsparam_string("xprtsec", Opt_xprtsec),
+ fsparam_flag ("fasc", Opt_fasc),
{}
};
@@ -925,6 +927,9 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
case Opt_sloppy:
ctx->sloppy = true;
break;
+ case Opt_fasc:
+ ctx->flags |= NFS_MOUNT_FASC;
+ break;
}
return 0;
@@ -448,6 +448,7 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
{ NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
{ NFS_MOUNT_UNSHARED, ",nosharecache", "" },
{ NFS_MOUNT_NORESVPORT, ",noresvport", "" },
+ { NFS_MOUNT_FASC, ",fasc", "" },
{ 0, NULL, NULL }
};
const struct proc_nfs_info *nfs_infop;
@@ -155,6 +155,7 @@ struct nfs_server {
#define NFS_MOUNT_WRITE_WAIT 0x02000000
#define NFS_MOUNT_TRUNK_DISCOVERY 0x04000000
#define NFS_MOUNT_SHUTDOWN 0x08000000
+#define NFS_MOUNT_FASC 0x10000000
unsigned int fattr_valid; /* Valid attributes */
unsigned int caps; /* server capabilities */
In certain instances, users or applications switch to other privileged users by executing commands like 'su' to carry out operations on NFS- mounted folders. However, when this happens, the login time for the privileged user is reset, and any NFS ACCESS operations must be resent, which can result in a decrease in performance. In specific production environments where the access cache can be trusted due to stable group membership, there's no need to verify the cache stall situation. To maintain the initial behavior and performance, a new mount option called 'fasc' has been introduced. This option triggers the mechanism of clearing the file access cache upon login. Signed-off-by: Chengen Du <chengen.du@canonical.com> --- fs/nfs/dir.c | 21 ++++++++++++--------- fs/nfs/fs_context.c | 5 +++++ fs/nfs/super.c | 1 + include/linux/nfs_fs_sb.h | 1 + 4 files changed, 19 insertions(+), 9 deletions(-)