----- Original Message ----- I'm by no means at all versed in the intracacies of NFS exports, but here's how I found the instance of an exported filesystem on a RHEL5 machine that exports its "/usr/dumps" directory. The nfsd module has a global "svc_export_cache" data structure that is declared in "fs/nfsd/export.c": struct cache_detail svc_export_cache = { .owner = THIS_MODULE, .hash_size = EXPORT_HASHMAX, .hash_table = export_table, .name = "nfsd.export", .cache_put = svc_export_put, .cache_request = svc_export_request, .cache_parse = svc_export_parse, .cache_show = svc_export_show, .match = svc_export_match, .init = svc_export_init, .update = export_update, .alloc = svc_export_alloc, }; Load the nfsd module's debuginfo data first: crash> mod -s nfsd MODULE NAME SIZE OBJECT FILE ffffffff88f2ae00 nfsd 285065 /lib/modules/2.6.18-128.el5/kernel/fs/nfsd/nfsd.ko crash> As I understand the kernel sources, each of the exported NFS filesystems are referenced by the by a "cache_head" structure that is contained in its "hash_table" array, which has "hash_size" entries: crash> cache_detail struct cache_detail { struct module *owner; int hash_size; <==== struct cache_head **hash_table; <==== rwlock_t hash_lock; atomic_t inuse; char *name; void (*cache_put)(struct kref *); void (*cache_request)(struct cache_detail *, struct cache_head *, char **, int *); int (*cache_parse)(struct cache_detail *, char *, int); int (*cache_show)(struct seq_file *, struct cache_detail *, struct cache_head *); struct cache_head *(*alloc)(void); int (*match)(struct cache_head *, struct cache_head *); void (*init)(struct cache_head *, struct cache_head *); void (*update)(struct cache_head *, struct cache_head *); time_t flush_time; struct list_head others; time_t nextcheck; int entries; struct list_head queue; struct proc_dir_entry *proc_ent; struct proc_dir_entry *flush_ent; struct proc_dir_entry *channel_ent; struct proc_dir_entry *content_ent; atomic_t readers; time_t last_close; time_t last_warn; void (*warn_no_listener)(struct cache_detail *); } SIZE: 224 crash> So if you look at the structure contents, there is an array of 256 cache_head structures at 0xffffffff88499b00: crash> svc_export_cache svc_export_cache = $4 = { owner = 0xffffffff88490f80, hash_size = 256, <==== hash_table = 0xffffffff88499b00, <==== hash_lock = { raw_lock = { lock = 16777216 } }, inuse = { counter = 0 }, name = 0xffffffff88481405 "nfsd.export", cache_put = 0xffffffff88469be3 <svc_export_put>, cache_request = 0xffffffff8846a581 <svc_export_request>, cache_parse = 0xffffffff8846ab86 <svc_export_parse>, cache_show = 0xffffffff88469306 <svc_export_show>, alloc = 0xffffffff8846924a <svc_export_alloc>, match = 0xffffffff884690a4 <svc_export_match>, init = 0xffffffff8846a762 <svc_export_init>, update = 0xffffffff884690ca <export_update>, flush_time = 1333389558, others = { next = 0xffffffff88428a50, prev = 0xffffffff8848f490 }, nextcheck = 1345127263, entries = 1, queue = { next = 0xffff810028f73cc0, prev = 0xffff810028f73cc0 }, proc_ent = 0xffff81003a7d4180, flush_ent = 0xffff8100389678c0, channel_ent = 0xffff8100389679c0, content_ent = 0xffff810038646b80, readers = { counter = 1 }, last_close = 1333389553, last_warn = -1, warn_no_listener = 0 } crash> And by dumping the 256 entries in the hash table, I see just the single entry down at address ffffffff8849a040: crash> rd 0xffffffff88499b00 256 ffffffff88499b00: 0000000000000000 0000000000000000 ................ ffffffff88499b10: 0000000000000000 0000000000000000 ................ ffffffff88499b20: 0000000000000000 0000000000000000 ................ ffffffff88499b30: 0000000000000000 0000000000000000 ................ ffffffff88499b40: 0000000000000000 0000000000000000 ................ ffffffff88499b50: 0000000000000000 0000000000000000 ................ ffffffff88499b60: 0000000000000000 0000000000000000 ................ ffffffff88499b70: 0000000000000000 0000000000000000 ................ ffffffff88499b80: 0000000000000000 0000000000000000 ................ ffffffff88499b90: 0000000000000000 0000000000000000 ................ ffffffff88499ba0: 0000000000000000 0000000000000000 ................ ffffffff88499bb0: 0000000000000000 0000000000000000 ................ ffffffff88499bc0: 0000000000000000 0000000000000000 ................ ffffffff88499bd0: 0000000000000000 0000000000000000 ................ ffffffff88499be0: 0000000000000000 0000000000000000 ................ ffffffff88499bf0: 0000000000000000 0000000000000000 ................ ffffffff88499c00: 0000000000000000 0000000000000000 ................ ffffffff88499c10: 0000000000000000 0000000000000000 ................ ffffffff88499c20: 0000000000000000 0000000000000000 ................ ffffffff88499c30: 0000000000000000 0000000000000000 ................ ffffffff88499c40: 0000000000000000 0000000000000000 ................ ffffffff88499c50: 0000000000000000 0000000000000000 ................ ffffffff88499c60: 0000000000000000 0000000000000000 ................ ffffffff88499c70: 0000000000000000 0000000000000000 ................ ffffffff88499c80: 0000000000000000 0000000000000000 ................ ffffffff88499c90: 0000000000000000 0000000000000000 ................ ffffffff88499ca0: 0000000000000000 0000000000000000 ................ ffffffff88499cb0: 0000000000000000 0000000000000000 ................ ffffffff88499cc0: 0000000000000000 0000000000000000 ................ ffffffff88499cd0: 0000000000000000 0000000000000000 ................ ffffffff88499ce0: 0000000000000000 0000000000000000 ................ ffffffff88499cf0: 0000000000000000 0000000000000000 ................ ffffffff88499d00: 0000000000000000 0000000000000000 ................ ffffffff88499d10: 0000000000000000 0000000000000000 ................ ffffffff88499d20: 0000000000000000 0000000000000000 ................ ffffffff88499d30: 0000000000000000 0000000000000000 ................ ffffffff88499d40: 0000000000000000 0000000000000000 ................ ffffffff88499d50: 0000000000000000 0000000000000000 ................ ffffffff88499d60: 0000000000000000 0000000000000000 ................ ffffffff88499d70: 0000000000000000 0000000000000000 ................ ffffffff88499d80: 0000000000000000 0000000000000000 ................ ffffffff88499d90: 0000000000000000 0000000000000000 ................ ffffffff88499da0: 0000000000000000 0000000000000000 ................ ffffffff88499db0: 0000000000000000 0000000000000000 ................ ffffffff88499dc0: 0000000000000000 0000000000000000 ................ ffffffff88499dd0: 0000000000000000 0000000000000000 ................ ffffffff88499de0: 0000000000000000 0000000000000000 ................ ffffffff88499df0: 0000000000000000 0000000000000000 ................ ffffffff88499e00: 0000000000000000 0000000000000000 ................ ffffffff88499e10: 0000000000000000 0000000000000000 ................ ffffffff88499e20: 0000000000000000 0000000000000000 ................ ffffffff88499e30: 0000000000000000 0000000000000000 ................ ffffffff88499e40: 0000000000000000 0000000000000000 ................ ffffffff88499e50: 0000000000000000 0000000000000000 ................ ffffffff88499e60: 0000000000000000 0000000000000000 ................ ffffffff88499e70: 0000000000000000 0000000000000000 ................ ffffffff88499e80: 0000000000000000 0000000000000000 ................ ffffffff88499e90: 0000000000000000 0000000000000000 ................ ffffffff88499ea0: 0000000000000000 0000000000000000 ................ ffffffff88499eb0: 0000000000000000 0000000000000000 ................ ffffffff88499ec0: 0000000000000000 0000000000000000 ................ ffffffff88499ed0: 0000000000000000 0000000000000000 ................ ffffffff88499ee0: 0000000000000000 0000000000000000 ................ ffffffff88499ef0: 0000000000000000 0000000000000000 ................ ffffffff88499f00: 0000000000000000 0000000000000000 ................ ffffffff88499f10: 0000000000000000 0000000000000000 ................ ffffffff88499f20: 0000000000000000 0000000000000000 ................ ffffffff88499f30: 0000000000000000 0000000000000000 ................ ffffffff88499f40: 0000000000000000 0000000000000000 ................ ffffffff88499f50: 0000000000000000 0000000000000000 ................ ffffffff88499f60: 0000000000000000 0000000000000000 ................ ffffffff88499f70: 0000000000000000 0000000000000000 ................ ffffffff88499f80: 0000000000000000 0000000000000000 ................ ffffffff88499f90: 0000000000000000 0000000000000000 ................ ffffffff88499fa0: 0000000000000000 0000000000000000 ................ ffffffff88499fb0: 0000000000000000 0000000000000000 ................ ffffffff88499fc0: 0000000000000000 0000000000000000 ................ ffffffff88499fd0: 0000000000000000 0000000000000000 ................ ffffffff88499fe0: 0000000000000000 0000000000000000 ................ ffffffff88499ff0: 0000000000000000 0000000000000000 ................ ffffffff8849a000: 0000000000000000 0000000000000000 ................ ffffffff8849a010: 0000000000000000 0000000000000000 ................ ffffffff8849a020: 0000000000000000 0000000000000000 ................ ffffffff8849a030: 0000000000000000 0000000000000000 ................ ffffffff8849a040: ffff810036155280 0000000000000000 .R.6............ ffffffff8849a050: 0000000000000000 0000000000000000 ................ ffffffff8849a060: 0000000000000000 0000000000000000 ................ ffffffff8849a070: 0000000000000000 0000000000000000 ................ ffffffff8849a080: 0000000000000000 0000000000000000 ................ ffffffff8849a090: 0000000000000000 0000000000000000 ................ ffffffff8849a0a0: 0000000000000000 0000000000000000 ................ ffffffff8849a0b0: 0000000000000000 0000000000000000 ................ ffffffff8849a0c0: 0000000000000000 0000000000000000 ................ ffffffff8849a0d0: 0000000000000000 0000000000000000 ................ ffffffff8849a0e0: 0000000000000000 0000000000000000 ................ ffffffff8849a0f0: 0000000000000000 0000000000000000 ................ ffffffff8849a100: 0000000000000000 0000000000000000 ................ ffffffff8849a110: 0000000000000000 0000000000000000 ................ ffffffff8849a120: 0000000000000000 0000000000000000 ................ ffffffff8849a130: 0000000000000000 0000000000000000 ................ ffffffff8849a140: 0000000000000000 0000000000000000 ................ ffffffff8849a150: 0000000000000000 0000000000000000 ................ ffffffff8849a160: 0000000000000000 0000000000000000 ................ ffffffff8849a170: 0000000000000000 0000000000000000 ................ ffffffff8849a180: 0000000000000000 0000000000000000 ................ ffffffff8849a190: 0000000000000000 0000000000000000 ................ ffffffff8849a1a0: 0000000000000000 0000000000000000 ................ ffffffff8849a1b0: 0000000000000000 0000000000000000 ................ ffffffff8849a1c0: 0000000000000000 0000000000000000 ................ ffffffff8849a1d0: 0000000000000000 0000000000000000 ................ ffffffff8849a1e0: 0000000000000000 0000000000000000 ................ ffffffff8849a1f0: 0000000000000000 0000000000000000 ................ ffffffff8849a200: 0000000000000000 0000000000000000 ................ ffffffff8849a210: 0000000000000000 0000000000000000 ................ ffffffff8849a220: 0000000000000000 0000000000000000 ................ ffffffff8849a230: 0000000000000000 0000000000000000 ................ ffffffff8849a240: 0000000000000000 0000000000000000 ................ ffffffff8849a250: 0000000000000000 0000000000000000 ................ ffffffff8849a260: 0000000000000000 0000000000000000 ................ ffffffff8849a270: 0000000000000000 0000000000000000 ................ ffffffff8849a280: 0000000000000000 0000000000000000 ................ ffffffff8849a290: 0000000000000000 0000000000000000 ................ ffffffff8849a2a0: 0000000000000000 0000000000000000 ................ ffffffff8849a2b0: 0000000000000000 0000000000000000 ................ ffffffff8849a2c0: 0000000000000000 0000000000000000 ................ ffffffff8849a2d0: 0000000000000000 0000000000000000 ................ ffffffff8849a2e0: 0000000000000000 0000000000000000 ................ ffffffff8849a2f0: 0000000000000000 0000000000000000 ................ crash> That cache_head looks like this: crash> cache_head ffff810036155280 struct cache_head { next = 0x0, expiry_time = 1345127262, last_refresh = 1345125462, ref = { refcount = { counter = 1 } }, flags = 1 } crash> But the cache_head is embedded in an svc_export structure: crash> svc_export struct svc_export { struct cache_head h; struct auth_domain *ex_client; int ex_flags; struct vfsmount *ex_mnt; struct dentry *ex_dentry; char *ex_path; uid_t ex_anon_uid; gid_t ex_anon_gid; int ex_fsid; struct nfsd4_fs_locations ex_fslocs; int ex_nflavors; struct exp_flavor_info ex_flavors[8]; } SIZE: 192 crash> And so looking at that entry as an svc_export, voila, we see the "/usr/dumps" export: crash> svc_export ffff810036155280 struct svc_export { h = { next = 0x0, expiry_time = 1345127262, last_refresh = 1345125462, ref = { refcount = { counter = 1 } }, flags = 1 }, ex_client = 0xffff810038abeb80, ex_flags = 47, ex_mnt = 0xffff81003fe13480, ex_dentry = 0xffff81001dee0660, ex_path = 0xffff81002a09c3e0 "/usr/dumps", <==== ex_anon_uid = 65534, ex_anon_gid = 65534, ex_fsid = 0, ex_fslocs = { locations_count = 0, locations = 0x0, migrated = 0 }, ex_nflavors = 0, ex_flavors = {{ pseudoflavor = 4294934784, flags = 835776256 }, { pseudoflavor = 4294934784, flags = 613611416 }, { pseudoflavor = 4294934784, flags = 687289760 }, { pseudoflavor = 4294934784, flags = 4 }, { pseudoflavor = 0, flags = 4 }, { pseudoflavor = 0, flags = 2148721614 }, { pseudoflavor = 4294967295, flags = 0 }, { pseudoflavor = 0, flags = 1352 }} } crash> Now, that all being done, that search could have been signicantly simplified given that the hash_table array is initialized to point to the static data strucure "export_table": struct cache_detail svc_export_cache = { .owner = THIS_MODULE, .hash_size = EXPORT_HASHMAX, .hash_table = export_table, <===== ... So if you just dump its contents directly: crash> p export_table export_table = $5 = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x 0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0 x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 , 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xffff810036155280, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x 0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0 x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0} crash> And then cast each non-zero entry in the array as an svc_export as done above. At least I *think* that's how it works... Dave

Hi Dave, Really Nice information, I am running Kernel 2.6.18-274 and will try to use the below pointers. Regards, Tipu.