From 238b351d0935df568ecb3dc5aef25971778f0f7c Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Wed, 30 Aug 2023 22:48:41 -0500
Subject: [PATCH 29/50] smb3: allow controlling length of time directory
entries are cached with dir leases
Currently with directory leases we cache directory contents for a fixed period
of time (default 30 seconds) but for many workloads this is too short. Allow
configuring the maximum amount of time directory entries are cached when a
directory lease is held on that directory. Add module load parm "max_dir_cache"
For example to set the timeout to 10 minutes you would do:
echo 600 > /sys/module/cifs/parameters/dir_cache_timeout
or to disable caching directory contents:
echo 0 > /sys/module/cifs/parameters/dir_cache_timeout
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
fs/smb/client/cached_dir.c | 4 ++--
fs/smb/client/cifsfs.c | 10 ++++++++++
fs/smb/client/cifsglob.h | 1 +
3 files changed, 13 insertions(+), 2 deletions(-)
@@ -145,7 +145,7 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
const char *npath;
if (tcon == NULL || tcon->cfids == NULL || tcon->nohandlecache ||
- is_smb1_server(tcon->ses->server))
+ is_smb1_server(tcon->ses->server) || (dir_cache_timeout == 0))
return -EOPNOTSUPP;
ses = tcon->ses;
@@ -582,7 +582,7 @@ cifs_cfids_laundromat_thread(void *p)
return 0;
spin_lock(&cfids->cfid_list_lock);
list_for_each_entry_safe(cfid, q, &cfids->entries, entry) {
- if (time_after(jiffies, cfid->time + HZ * 30)) {
+ if (time_after(jiffies, cfid->time + HZ * dir_cache_timeout)) {
list_del(&cfid->entry);
list_add(&cfid->entry, &entry);
cfids->num_entries--;
@@ -117,6 +117,10 @@ module_param(cifs_max_pending, uint, 0444);
MODULE_PARM_DESC(cifs_max_pending, "Simultaneous requests to server for "
"CIFS/SMB1 dialect (N/A for SMB3) "
"Default: 32767 Range: 2 to 32767.");
+unsigned int dir_cache_timeout = 30;
+module_param(dir_cache_timeout, uint, 0644);
+MODULE_PARM_DESC(dir_cache_timeout, "Number of seconds to cache directory contents for which we have a lease. Default: 30 "
+ "Range: 1 to 65000 seconds, 0 to disable caching dir contents");
#ifdef CONFIG_CIFS_STATS2
unsigned int slow_rsp_threshold = 1;
module_param(slow_rsp_threshold, uint, 0644);
@@ -1679,6 +1683,12 @@ init_cifs(void)
CIFS_MAX_REQ);
}
+ /* Limit max to about 18 hours, and setting to zero disables directory entry caching */
+ if (dir_cache_timeout > 65000) {
+ dir_cache_timeout = 65000;
+ cifs_dbg(VFS, "dir_cache_timeout set to max of 65000 seconds\n");
+ }
+
cifsiod_wq = alloc_workqueue("cifsiod", WQ_FREEZABLE|WQ_MEM_RECLAIM, 0);
if (!cifsiod_wq) {
rc = -ENOMEM;
@@ -2016,6 +2016,7 @@ extern unsigned int CIFSMaxBufSize; /* max size not including hdr */
extern unsigned int cifs_min_rcv; /* min size of big ntwrk buf pool */
extern unsigned int cifs_min_small; /* min size of small buf pool */
extern unsigned int cifs_max_pending; /* MAX requests at once to server*/
+extern unsigned int dir_cache_timeout; /* max time for directory lease caching of dir */
extern bool disable_legacy_dialects; /* forbid vers=1.0 and vers=2.0 mounts */
extern atomic_t mid_count;
--
2.39.2
There were a set of issues brought up in 6.5 by the introduction of the "laundromat" (which cleans up directory leases). After discussion and testing with Paulo, Bernd Feige and others, we request that the following set also be included to address these problems. They are all in mainline (added in 6.6) and the patches (from mainline since they apply cleanly) are also attached. 238b351d0935 ("smb3: allow controlling length of time directory entries are cached with dir leases") 6a50d71d0fff ("smb3: allow controlling maximum number of cached directories") 2da338ff752a ("smb3: do not start laundromat thread when dir leases disabled") 3b8bb3171571 ("smb: client: do not start laundromat thread on nohandlecache") e95f3f744650 ("smb: client: make laundromat a delayed worker") 81ba10959970 ("smb: client: prevent new fids from being removed by laundromat")