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smb: client: add drop_dir_cache module parameter to invalidate cached dirents

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Add write-only /sys/module/cifs/parameters/drop_dir_cache. Writing a
non-zero value iterates all tcons and calls invalidate_all_cached_dirs()
to drop cached directory entries. This is useful to force a dirent cache
drop across mounts for debugging and testing purpose.

Signed-off-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Bharath SM
2025-09-02 01:16:00 +05:30
committed by Steve French
parent ac3ad9845b
commit dde6667fa3
1 changed files with 38 additions and 0 deletions
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38
fs/smb/client/cifsfs.c
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@@ -121,6 +121,44 @@ 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");
/*
* Write-only module parameter to drop all cached directory entries across
* all CIFS mounts. Echo a non-zero value to trigger.
*/
static void cifs_drop_all_dir_caches(void)
{
struct TCP_Server_Info *server;
struct cifs_ses *ses;
struct cifs_tcon *tcon;
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
if (cifs_ses_exiting(ses))
continue;
list_for_each_entry(tcon, &ses->tcon_list, tcon_list)
invalidate_all_cached_dirs(tcon);
}
}
spin_unlock(&cifs_tcp_ses_lock);
}
static int cifs_param_set_drop_dir_cache(const char *val, const struct kernel_param *kp)
{
bool bv;
int rc = kstrtobool(val, &bv);
if (rc)
return rc;
if (bv)
cifs_drop_all_dir_caches();
return 0;
}
module_param_call(drop_dir_cache, cifs_param_set_drop_dir_cache, NULL, NULL, 0200);
MODULE_PARM_DESC(drop_dir_cache, "Write 1 to drop all cached directory entries across all CIFS mounts");
#ifdef CONFIG_CIFS_STATS2
unsigned int slow_rsp_threshold = 1;
module_param(slow_rsp_threshold, uint, 0644);