{"id":2229708,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2229708/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260428160804.281745-12-sprasad@microsoft.com/","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/1.1/projects/12/?format=json","name":"Linux CIFS Client","link_name":"linux-cifs-client","list_id":"linux-cifs.vger.kernel.org","list_email":"linux-cifs@vger.kernel.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260428160804.281745-12-sprasad@microsoft.com>","date":"2026-04-28T16:07:57","name":"[v3,12/19] cifs: register a shrinker to manage cached_dirents","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"a42cc0ae9c4659f2bcb01e8df06fcea845a0043b","submitter":{"id":79368,"url":"http://patchwork.ozlabs.org/api/1.1/people/79368/?format=json","name":"Shyam Prasad N","email":"nspmangalore@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260428160804.281745-12-sprasad@microsoft.com/mbox/","series":[{"id":501896,"url":"http://patchwork.ozlabs.org/api/1.1/series/501896/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=501896","date":"2026-04-28T16:07:57","name":"[v3,01/19] cifs: change_conf needs to be called for session setup","version":3,"mbox":"http://patchwork.ozlabs.org/series/501896/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2229708/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2229708/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-cifs@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=rWqqXbxr;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c09:e001:a7::12fc:5321; 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This change registers a\nshrinker with the mm layer for the dircache. If mm needs to free up\nmemory or flush the cache, it can inform cifs about this using the\nshrinker interface.\n\nSigned-off-by: Shyam Prasad N \n---\n fs/smb/client/cifsfs.c | 86 +++++++++++++++++++++++++++++++++++++++---\n 1 file changed, 80 insertions(+), 6 deletions(-)","diff":"diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c\nindex 32d0305a1239a..ee5de358e27f8 100644\n--- a/fs/smb/client/cifsfs.c\n+++ b/fs/smb/client/cifsfs.c\n@@ -29,6 +29,7 @@\n #include \n #include \n #include \n+#include \n #include \n #include \n #include \n@@ -123,27 +124,86 @@ MODULE_PARM_DESC(dir_cache_timeout, \"Number of seconds to cache directory conten\n \t\t\t\t \"Range: 1 to 65000 seconds, 0 to disable caching dir contents\");\n /* Module-wide total cached dirents (in bytes) across all tcons */\n atomic64_t cifs_dircache_bytes_used = ATOMIC64_INIT(0);\n+static struct shrinker *cifs_dircache_shrinker;\n \n /*\n * Write-only module parameter to drop all cached directory entries across\n * all CIFS mounts. Echo a non-zero value to trigger.\n */\n-static void cifs_drop_all_dir_caches(void)\n+static unsigned long cifs_drop_all_dir_caches(bool wait, unsigned long nr_to_free)\n {\n \tstruct TCP_Server_Info *server;\n \tstruct cifs_ses *ses;\n \tstruct cifs_tcon *tcon;\n+\tu64 before, after, freed_bytes = 0;\n+\tu64 target_bytes;\n+\n+\tbefore = atomic64_read(&cifs_dircache_bytes_used);\n+\tif (nr_to_free == ULONG_MAX)\n+\t\ttarget_bytes = U64_MAX;\n+\telse\n+\t\ttarget_bytes = (u64)nr_to_free * PAGE_SIZE;\n \n \tspin_lock(&cifs_tcp_ses_lock);\n \tlist_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {\n \t\tlist_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {\n \t\t\tif (cifs_ses_exiting(ses))\n \t\t\t\tcontinue;\n-\t\t\tlist_for_each_entry(tcon, &ses->tcon_list, tcon_list)\n-\t\t\t\tinvalidate_all_cached_dirs(tcon);\n+\t\t\tlist_for_each_entry(tcon, &ses->tcon_list, tcon_list) {\n+\t\t\t\tinvalidate_all_cached_dirs_nowait(tcon);\n+\t\t\t\tafter = atomic64_read(&cifs_dircache_bytes_used);\n+\t\t\t\tif (after < before)\n+\t\t\t\t\tfreed_bytes = before - after;\n+\t\t\t\tif (freed_bytes >= target_bytes)\n+\t\t\t\t\tgoto out_unlock;\n+\t\t\t}\n \t\t}\n \t}\n+out_unlock:\n \tspin_unlock(&cifs_tcp_ses_lock);\n+\n+\tif (wait)\n+\t\tflush_workqueue(cfid_put_wq);\n+\n+\tafter = atomic64_read(&cifs_dircache_bytes_used);\n+\tif (after >= before)\n+\t\treturn 0;\n+\treturn (unsigned long)(before - after);\n+}\n+\n+static unsigned long cifs_dircache_shrinker_count(struct shrinker *shrink,\n+\t\t\t\t\t\t struct shrink_control *sc)\n+{\n+\tu64 bytes = atomic64_read(&cifs_dircache_bytes_used);\n+\n+\t(void)shrink;\n+\t(void)sc;\n+\n+\treturn DIV_ROUND_UP_ULL(bytes, PAGE_SIZE);\n+}\n+\n+static unsigned long cifs_dircache_shrinker_scan(struct shrinker *shrink,\n+\t\t\t\t\t\t struct shrink_control *sc)\n+{\n+\tunsigned long freed_bytes;\n+\n+\t(void)shrink;\n+\n+\tif (!sc->nr_to_scan)\n+\t\treturn 0;\n+\n+\tif (!atomic64_read(&cifs_dircache_bytes_used))\n+\t\treturn SHRINK_STOP;\n+\n+\t/*\n+\t * Shrinker scan can run from reclaim context, so avoid synchronously\n+\t * flushing worker queues here to prevent long stalls/deadlocks.\n+\t */\n+\tfreed_bytes = cifs_drop_all_dir_caches(false, max_t(unsigned long, 1, sc->nr_to_scan));\n+\tif (!freed_bytes)\n+\t\treturn SHRINK_STOP;\n+\n+\treturn DIV_ROUND_UP_ULL(freed_bytes, PAGE_SIZE);\n }\n \n static int cifs_param_set_drop_dir_cache(const char *val, const struct kernel_param *kp)\n@@ -154,7 +214,7 @@ static int cifs_param_set_drop_dir_cache(const char *val, const struct kernel_pa\n \tif (rc)\n \t\treturn rc;\n \tif (bv)\n-\t\tcifs_drop_all_dir_caches();\n+\t\tcifs_drop_all_dir_caches(true, ULONG_MAX);\n \treturn 0;\n }\n \n@@ -2038,10 +2098,19 @@ init_cifs(void)\n \tif (rc)\n \t\tgoto out_destroy_mids;\n \n+\tcifs_dircache_shrinker = shrinker_alloc(0, \"cifs-dircache\");\n+\tif (!cifs_dircache_shrinker) {\n+\t\trc = -ENOMEM;\n+\t\tgoto out_destroy_request_bufs;\n+\t}\n+\tcifs_dircache_shrinker->count_objects = cifs_dircache_shrinker_count;\n+\tcifs_dircache_shrinker->scan_objects = cifs_dircache_shrinker_scan;\n+\tshrinker_register(cifs_dircache_shrinker);\n+\n #ifdef CONFIG_CIFS_DFS_UPCALL\n \trc = dfs_cache_init();\n \tif (rc)\n-\t\tgoto out_destroy_request_bufs;\n+\t\tgoto out_free_dircache_shrinker;\n #endif /* CONFIG_CIFS_DFS_UPCALL */\n #ifdef CONFIG_CIFS_UPCALL\n \trc = init_cifs_spnego();\n@@ -2083,8 +2152,11 @@ init_cifs(void)\n #endif\n #ifdef CONFIG_CIFS_DFS_UPCALL\n \tdfs_cache_destroy();\n-out_destroy_request_bufs:\n+out_free_dircache_shrinker:\n #endif\n+\tshrinker_free(cifs_dircache_shrinker);\n+\tcifs_dircache_shrinker = NULL;\n+out_destroy_request_bufs:\n \tcifs_destroy_request_bufs();\n out_destroy_mids:\n \tdestroy_mids();\n@@ -2117,6 +2189,8 @@ exit_cifs(void)\n \tcifs_dbg(NOISY, \"exit_smb3\\n\");\n \tunregister_filesystem(&cifs_fs_type);\n \tunregister_filesystem(&smb3_fs_type);\n+\tshrinker_free(cifs_dircache_shrinker);\n+\tcifs_dircache_shrinker = NULL;\n \tcifs_release_automount_timer();\n \texit_cifs_idmap();\n #ifdef CONFIG_CIFS_SWN_UPCALL\n","prefixes":["v3","12/19"]}