![J. Bruce Fields](/assets/img/avatar_default.png)
Thanks to Matthew Dodd for this bug report: A file label issue while running SELinux in MLS mode provoked the following bug, which is a result of use before init on a 'struct list_head'. In nfsd4_list_rec_dir() if the call to dentry_open() fails the 'goto out' skips INIT_LIST_HEAD() which results in the normally improbable case where list_entry() returns NULL. Trace follows. NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state recovery directory SELinux: Context unconfined_t:object_r:var_lib_nfs_t:s0 is not valid (left unmapped). type=1400 audit(1227298063.609:282): avc: denied { read } for pid=1890 comm="rpc.nfsd" name="v4recovery" dev=dm-0 ino=148726 scontext=system_u:system_r:nfsd_t:s0-s15:c0.c1023 tcontext=system_u:object_r:unlabeled_t:s15:c0.c1023 tclass=dir BUG: unable to handle kernel NULL pointer dereference at 00000004 IP: [<c050894e>] list_del+0x6/0x60 *pde = 0d9ce067 *pte = 00000000 Oops: 0000 [#1] SMP Modules linked in: nfsd lockd nfs_acl auth_rpcgss exportfs autofs4 sunrpc ipv6 dm_multipath scsi_dh ppdev parport_pc sg parport floppy ata_piix pata_acpi ata_generic libata pcnet32 i2c_piix4 mii pcspkr i2c_core dm_snapshot dm_zero dm_mirror dm_log dm_mod BusLogic sd_mod scsi_mod crc_t10dif ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd [last unloaded: microcode] Pid: 1890, comm: rpc.nfsd Not tainted (2.6.27.5-37.fc9.i686 #1) EIP: 0060:[<c050894e>] EFLAGS: 00010217 CPU: 0 EIP is at list_del+0x6/0x60 EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: cd99e480 ESI: cf9caed8 EDI: 00000000 EBP: cf9caebc ESP: cf9caeb8 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 Process rpc.nfsd (pid: 1890, ti=cf9ca000 task=cf4de580 task.ti=cf9ca000) Stack: 00000000 cf9caef0 d0a9f139 c0496d04 d0a9f217 fffffff3 00000000 00000000 00000000 00000000 cf32b220 00000000 00000008 00000801 cf9caefc d0a9f193 00000000 cf9caf08 d0a9b6ea 00000000 cf9caf1c d0a874f2 cf9c3004 00000008 Call Trace: [<d0a9f139>] ? nfsd4_list_rec_dir+0xf3/0x13a [nfsd] [<c0496d04>] ? do_path_lookup+0x12d/0x175 [<d0a9f217>] ? load_recdir+0x0/0x26 [nfsd] [<d0a9f193>] ? nfsd4_recdir_load+0x13/0x34 [nfsd] [<d0a9b6ea>] ? nfs4_state_start+0x2a/0xc5 [nfsd] [<d0a874f2>] ? nfsd_svc+0x51/0xff [nfsd] [<d0a87f2d>] ? write_svc+0x0/0x1e [nfsd] [<d0a87f48>] ? write_svc+0x1b/0x1e [nfsd] [<d0a87854>] ? nfsctl_transaction_write+0x3a/0x61 [nfsd] [<c04b6a4e>] ? sys_nfsservctl+0x116/0x154 [<c04975c1>] ? putname+0x24/0x2f [<c04975c1>] ? putname+0x24/0x2f [<c048d49f>] ? do_sys_open+0xad/0xb7 [<c048d337>] ? filp_close+0x50/0x5a [<c048d4eb>] ? sys_open+0x1e/0x26 [<c0403cca>] ? syscall_call+0x7/0xb [<c064007b>] ? init_cyrix+0x185/0x490 ======================= Code: 75 e1 8b 53 08 8d 4b 04 8d 46 04 e8 75 00 00 00 8b 53 10 8d 4b 0c 8d 46 0c e8 67 00 00 00 5b 5e 5f 5d c3 90 90 55 89 e5 53 89 c3 <8b> 40 04 8b 00 39 d8 74 16 50 53 68 3e d6 6f c0 6a 30 68 78 d6 EIP: [<c050894e>] list_del+0x6/0x60 SS:ESP 0068:cf9caeb8 ---[ end trace a89c4ad091c4ad53 ]--- Cc: Matthew N. Dodd <Matthew.Dodd@spart.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
434 lines
10 KiB
C
434 lines
10 KiB
C
/*
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* linux/fs/nfsd/nfs4recover.c
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*
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* Copyright (c) 2004 The Regents of the University of Michigan.
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* All rights reserved.
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*
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* Andy Adamson <andros@citi.umich.edu>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <linux/err.h>
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#include <linux/sunrpc/svc.h>
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#include <linux/nfsd/nfsd.h>
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#include <linux/nfs4.h>
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#include <linux/nfsd/state.h>
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#include <linux/nfsd/xdr4.h>
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#include <linux/param.h>
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#include <linux/file.h>
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#include <linux/namei.h>
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#include <asm/uaccess.h>
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#include <linux/scatterlist.h>
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#include <linux/crypto.h>
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#include <linux/sched.h>
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#include <linux/mount.h>
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#define NFSDDBG_FACILITY NFSDDBG_PROC
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/* Globals */
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static struct path rec_dir;
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static int rec_dir_init = 0;
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static void
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nfs4_save_user(uid_t *saveuid, gid_t *savegid)
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{
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*saveuid = current->fsuid;
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*savegid = current->fsgid;
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current->fsuid = 0;
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current->fsgid = 0;
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}
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static void
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nfs4_reset_user(uid_t saveuid, gid_t savegid)
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{
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current->fsuid = saveuid;
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current->fsgid = savegid;
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}
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static void
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md5_to_hex(char *out, char *md5)
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{
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int i;
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for (i=0; i<16; i++) {
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unsigned char c = md5[i];
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*out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
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*out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
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}
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*out = '\0';
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}
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__be32
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nfs4_make_rec_clidname(char *dname, struct xdr_netobj *clname)
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{
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struct xdr_netobj cksum;
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struct hash_desc desc;
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struct scatterlist sg;
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__be32 status = nfserr_resource;
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dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
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clname->len, clname->data);
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desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
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desc.tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(desc.tfm))
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goto out_no_tfm;
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cksum.len = crypto_hash_digestsize(desc.tfm);
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cksum.data = kmalloc(cksum.len, GFP_KERNEL);
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if (cksum.data == NULL)
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goto out;
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sg_init_one(&sg, clname->data, clname->len);
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if (crypto_hash_digest(&desc, &sg, sg.length, cksum.data))
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goto out;
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md5_to_hex(dname, cksum.data);
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kfree(cksum.data);
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status = nfs_ok;
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out:
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crypto_free_hash(desc.tfm);
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out_no_tfm:
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return status;
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}
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static void
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nfsd4_sync_rec_dir(void)
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{
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mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
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nfsd_sync_dir(rec_dir.dentry);
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mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
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}
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int
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nfsd4_create_clid_dir(struct nfs4_client *clp)
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{
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char *dname = clp->cl_recdir;
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struct dentry *dentry;
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uid_t uid;
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gid_t gid;
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int status;
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dprintk("NFSD: nfsd4_create_clid_dir for \"%s\"\n", dname);
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if (!rec_dir_init || clp->cl_firststate)
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return 0;
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nfs4_save_user(&uid, &gid);
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/* lock the parent */
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mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
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dentry = lookup_one_len(dname, rec_dir.dentry, HEXDIR_LEN-1);
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if (IS_ERR(dentry)) {
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status = PTR_ERR(dentry);
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goto out_unlock;
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}
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status = -EEXIST;
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if (dentry->d_inode) {
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dprintk("NFSD: nfsd4_create_clid_dir: DIRECTORY EXISTS\n");
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goto out_put;
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}
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status = mnt_want_write(rec_dir.mnt);
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if (status)
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goto out_put;
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status = vfs_mkdir(rec_dir.dentry->d_inode, dentry, S_IRWXU);
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mnt_drop_write(rec_dir.mnt);
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out_put:
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dput(dentry);
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out_unlock:
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mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
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if (status == 0) {
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clp->cl_firststate = 1;
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nfsd4_sync_rec_dir();
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}
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nfs4_reset_user(uid, gid);
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dprintk("NFSD: nfsd4_create_clid_dir returns %d\n", status);
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return status;
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}
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typedef int (recdir_func)(struct dentry *, struct dentry *);
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struct dentry_list {
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struct dentry *dentry;
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struct list_head list;
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};
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struct dentry_list_arg {
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struct list_head dentries;
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struct dentry *parent;
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};
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static int
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nfsd4_build_dentrylist(void *arg, const char *name, int namlen,
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loff_t offset, u64 ino, unsigned int d_type)
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{
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struct dentry_list_arg *dla = arg;
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struct list_head *dentries = &dla->dentries;
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struct dentry *parent = dla->parent;
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struct dentry *dentry;
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struct dentry_list *child;
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if (name && isdotent(name, namlen))
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return 0;
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dentry = lookup_one_len(name, parent, namlen);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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child = kmalloc(sizeof(*child), GFP_KERNEL);
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if (child == NULL)
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return -ENOMEM;
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child->dentry = dentry;
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list_add(&child->list, dentries);
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return 0;
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}
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static int
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nfsd4_list_rec_dir(struct dentry *dir, recdir_func *f)
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{
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struct file *filp;
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struct dentry_list_arg dla = {
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.parent = dir,
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};
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struct list_head *dentries = &dla.dentries;
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struct dentry_list *child;
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uid_t uid;
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gid_t gid;
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int status;
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if (!rec_dir_init)
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return 0;
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nfs4_save_user(&uid, &gid);
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INIT_LIST_HEAD(dentries);
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filp = dentry_open(dget(dir), mntget(rec_dir.mnt), O_RDONLY);
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status = PTR_ERR(filp);
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if (IS_ERR(filp))
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goto out;
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status = vfs_readdir(filp, nfsd4_build_dentrylist, &dla);
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fput(filp);
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while (!list_empty(dentries)) {
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child = list_entry(dentries->next, struct dentry_list, list);
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status = f(dir, child->dentry);
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if (status)
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goto out;
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list_del(&child->list);
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dput(child->dentry);
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kfree(child);
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}
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out:
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while (!list_empty(dentries)) {
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child = list_entry(dentries->next, struct dentry_list, list);
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list_del(&child->list);
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dput(child->dentry);
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kfree(child);
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}
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nfs4_reset_user(uid, gid);
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return status;
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}
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static int
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nfsd4_remove_clid_file(struct dentry *dir, struct dentry *dentry)
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{
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int status;
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if (!S_ISREG(dir->d_inode->i_mode)) {
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printk("nfsd4: non-file found in client recovery directory\n");
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return -EINVAL;
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}
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mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
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status = vfs_unlink(dir->d_inode, dentry);
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mutex_unlock(&dir->d_inode->i_mutex);
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return status;
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}
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static int
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nfsd4_clear_clid_dir(struct dentry *dir, struct dentry *dentry)
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{
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int status;
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/* For now this directory should already be empty, but we empty it of
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* any regular files anyway, just in case the directory was created by
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* a kernel from the future.... */
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nfsd4_list_rec_dir(dentry, nfsd4_remove_clid_file);
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mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
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status = vfs_rmdir(dir->d_inode, dentry);
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mutex_unlock(&dir->d_inode->i_mutex);
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return status;
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}
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static int
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nfsd4_unlink_clid_dir(char *name, int namlen)
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{
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struct dentry *dentry;
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int status;
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dprintk("NFSD: nfsd4_unlink_clid_dir. name %.*s\n", namlen, name);
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mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
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dentry = lookup_one_len(name, rec_dir.dentry, namlen);
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mutex_unlock(&rec_dir.dentry->d_inode->i_mutex);
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if (IS_ERR(dentry)) {
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status = PTR_ERR(dentry);
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return status;
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}
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status = -ENOENT;
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if (!dentry->d_inode)
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goto out;
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status = nfsd4_clear_clid_dir(rec_dir.dentry, dentry);
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out:
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dput(dentry);
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return status;
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}
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void
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nfsd4_remove_clid_dir(struct nfs4_client *clp)
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{
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uid_t uid;
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gid_t gid;
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int status;
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if (!rec_dir_init || !clp->cl_firststate)
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return;
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status = mnt_want_write(rec_dir.mnt);
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if (status)
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goto out;
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clp->cl_firststate = 0;
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nfs4_save_user(&uid, &gid);
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status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);
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nfs4_reset_user(uid, gid);
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if (status == 0)
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nfsd4_sync_rec_dir();
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mnt_drop_write(rec_dir.mnt);
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out:
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if (status)
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printk("NFSD: Failed to remove expired client state directory"
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" %.*s\n", HEXDIR_LEN, clp->cl_recdir);
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return;
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}
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static int
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purge_old(struct dentry *parent, struct dentry *child)
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{
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int status;
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if (nfs4_has_reclaimed_state(child->d_name.name))
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return 0;
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status = nfsd4_clear_clid_dir(parent, child);
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if (status)
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printk("failed to remove client recovery directory %s\n",
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child->d_name.name);
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/* Keep trying, success or failure: */
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return 0;
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}
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void
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nfsd4_recdir_purge_old(void) {
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int status;
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if (!rec_dir_init)
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return;
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status = mnt_want_write(rec_dir.mnt);
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if (status)
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goto out;
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status = nfsd4_list_rec_dir(rec_dir.dentry, purge_old);
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if (status == 0)
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nfsd4_sync_rec_dir();
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mnt_drop_write(rec_dir.mnt);
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out:
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if (status)
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printk("nfsd4: failed to purge old clients from recovery"
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" directory %s\n", rec_dir.dentry->d_name.name);
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}
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static int
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load_recdir(struct dentry *parent, struct dentry *child)
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{
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if (child->d_name.len != HEXDIR_LEN - 1) {
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printk("nfsd4: illegal name %s in recovery directory\n",
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child->d_name.name);
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/* Keep trying; maybe the others are OK: */
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return 0;
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}
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nfs4_client_to_reclaim(child->d_name.name);
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return 0;
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}
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int
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nfsd4_recdir_load(void) {
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int status;
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status = nfsd4_list_rec_dir(rec_dir.dentry, load_recdir);
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if (status)
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printk("nfsd4: failed loading clients from recovery"
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" directory %s\n", rec_dir.dentry->d_name.name);
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return status;
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}
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/*
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* Hold reference to the recovery directory.
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*/
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void
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nfsd4_init_recdir(char *rec_dirname)
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{
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uid_t uid = 0;
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gid_t gid = 0;
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int status;
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printk("NFSD: Using %s as the NFSv4 state recovery directory\n",
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rec_dirname);
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BUG_ON(rec_dir_init);
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nfs4_save_user(&uid, &gid);
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status = kern_path(rec_dirname, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
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&rec_dir);
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if (status)
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printk("NFSD: unable to find recovery directory %s\n",
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rec_dirname);
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if (!status)
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rec_dir_init = 1;
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nfs4_reset_user(uid, gid);
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}
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void
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nfsd4_shutdown_recdir(void)
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{
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if (!rec_dir_init)
|
|
return;
|
|
rec_dir_init = 0;
|
|
path_put(&rec_dir);
|
|
}
|