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512 lines
12 KiB
512 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved |
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* Copyright 2001-2006 Ian Kent <[email protected]> |
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*/ |
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|
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#include <linux/sched/signal.h> |
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#include "autofs_i.h" |
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|
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/* We make this a static variable rather than a part of the superblock; it |
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* is better if we don't reassign numbers easily even across filesystems |
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*/ |
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static autofs_wqt_t autofs_next_wait_queue = 1; |
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void autofs_catatonic_mode(struct autofs_sb_info *sbi) |
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{ |
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struct autofs_wait_queue *wq, *nwq; |
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mutex_lock(&sbi->wq_mutex); |
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if (sbi->flags & AUTOFS_SBI_CATATONIC) { |
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mutex_unlock(&sbi->wq_mutex); |
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return; |
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} |
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pr_debug("entering catatonic mode\n"); |
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sbi->flags |= AUTOFS_SBI_CATATONIC; |
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wq = sbi->queues; |
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sbi->queues = NULL; /* Erase all wait queues */ |
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while (wq) { |
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nwq = wq->next; |
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wq->status = -ENOENT; /* Magic is gone - report failure */ |
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kfree(wq->name.name - wq->offset); |
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wq->name.name = NULL; |
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wq->wait_ctr--; |
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wake_up_interruptible(&wq->queue); |
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wq = nwq; |
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} |
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fput(sbi->pipe); /* Close the pipe */ |
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sbi->pipe = NULL; |
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sbi->pipefd = -1; |
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mutex_unlock(&sbi->wq_mutex); |
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} |
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static int autofs_write(struct autofs_sb_info *sbi, |
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struct file *file, const void *addr, int bytes) |
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{ |
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unsigned long sigpipe, flags; |
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const char *data = (const char *)addr; |
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ssize_t wr = 0; |
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sigpipe = sigismember(¤t->pending.signal, SIGPIPE); |
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mutex_lock(&sbi->pipe_mutex); |
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while (bytes) { |
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wr = __kernel_write(file, data, bytes, NULL); |
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if (wr <= 0) |
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break; |
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data += wr; |
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bytes -= wr; |
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} |
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mutex_unlock(&sbi->pipe_mutex); |
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/* Keep the currently executing process from receiving a |
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* SIGPIPE unless it was already supposed to get one |
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*/ |
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if (wr == -EPIPE && !sigpipe) { |
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spin_lock_irqsave(¤t->sighand->siglock, flags); |
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sigdelset(¤t->pending.signal, SIGPIPE); |
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recalc_sigpending(); |
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spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
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} |
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/* if 'wr' returned 0 (impossible) we assume -EIO (safe) */ |
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return bytes == 0 ? 0 : wr < 0 ? wr : -EIO; |
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} |
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static void autofs_notify_daemon(struct autofs_sb_info *sbi, |
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struct autofs_wait_queue *wq, |
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int type) |
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{ |
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union { |
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struct autofs_packet_hdr hdr; |
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union autofs_packet_union v4_pkt; |
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union autofs_v5_packet_union v5_pkt; |
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} pkt; |
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struct file *pipe = NULL; |
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size_t pktsz; |
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int ret; |
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pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n", |
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(unsigned long) wq->wait_queue_token, |
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wq->name.len, wq->name.name, type); |
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memset(&pkt, 0, sizeof(pkt)); /* For security reasons */ |
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pkt.hdr.proto_version = sbi->version; |
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pkt.hdr.type = type; |
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switch (type) { |
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/* Kernel protocol v4 missing and expire packets */ |
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case autofs_ptype_missing: |
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{ |
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struct autofs_packet_missing *mp = &pkt.v4_pkt.missing; |
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pktsz = sizeof(*mp); |
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mp->wait_queue_token = wq->wait_queue_token; |
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mp->len = wq->name.len; |
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memcpy(mp->name, wq->name.name, wq->name.len); |
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mp->name[wq->name.len] = '\0'; |
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break; |
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} |
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case autofs_ptype_expire_multi: |
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{ |
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struct autofs_packet_expire_multi *ep = |
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&pkt.v4_pkt.expire_multi; |
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pktsz = sizeof(*ep); |
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ep->wait_queue_token = wq->wait_queue_token; |
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ep->len = wq->name.len; |
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memcpy(ep->name, wq->name.name, wq->name.len); |
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ep->name[wq->name.len] = '\0'; |
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break; |
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} |
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/* |
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* Kernel protocol v5 packet for handling indirect and direct |
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* mount missing and expire requests |
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*/ |
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case autofs_ptype_missing_indirect: |
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case autofs_ptype_expire_indirect: |
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case autofs_ptype_missing_direct: |
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case autofs_ptype_expire_direct: |
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{ |
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struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet; |
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struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns; |
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pktsz = sizeof(*packet); |
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packet->wait_queue_token = wq->wait_queue_token; |
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packet->len = wq->name.len; |
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memcpy(packet->name, wq->name.name, wq->name.len); |
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packet->name[wq->name.len] = '\0'; |
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packet->dev = wq->dev; |
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packet->ino = wq->ino; |
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packet->uid = from_kuid_munged(user_ns, wq->uid); |
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packet->gid = from_kgid_munged(user_ns, wq->gid); |
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packet->pid = wq->pid; |
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packet->tgid = wq->tgid; |
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break; |
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} |
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default: |
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pr_warn("bad type %d!\n", type); |
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mutex_unlock(&sbi->wq_mutex); |
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return; |
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} |
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pipe = get_file(sbi->pipe); |
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mutex_unlock(&sbi->wq_mutex); |
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switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) { |
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case 0: |
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break; |
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case -ENOMEM: |
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case -ERESTARTSYS: |
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/* Just fail this one */ |
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autofs_wait_release(sbi, wq->wait_queue_token, ret); |
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break; |
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default: |
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autofs_catatonic_mode(sbi); |
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break; |
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} |
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fput(pipe); |
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} |
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static struct autofs_wait_queue * |
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autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr) |
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{ |
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struct autofs_wait_queue *wq; |
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for (wq = sbi->queues; wq; wq = wq->next) { |
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if (wq->name.hash == qstr->hash && |
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wq->name.len == qstr->len && |
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wq->name.name && |
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!memcmp(wq->name.name, qstr->name, qstr->len)) |
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break; |
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} |
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return wq; |
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} |
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/* |
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* Check if we have a valid request. |
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* Returns |
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* 1 if the request should continue. |
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* In this case we can return an autofs_wait_queue entry if one is |
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* found or NULL to idicate a new wait needs to be created. |
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* 0 or a negative errno if the request shouldn't continue. |
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*/ |
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static int validate_request(struct autofs_wait_queue **wait, |
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struct autofs_sb_info *sbi, |
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const struct qstr *qstr, |
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const struct path *path, enum autofs_notify notify) |
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{ |
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struct dentry *dentry = path->dentry; |
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struct autofs_wait_queue *wq; |
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struct autofs_info *ino; |
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if (sbi->flags & AUTOFS_SBI_CATATONIC) |
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return -ENOENT; |
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/* Wait in progress, continue; */ |
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wq = autofs_find_wait(sbi, qstr); |
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if (wq) { |
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*wait = wq; |
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return 1; |
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} |
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*wait = NULL; |
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/* If we don't yet have any info this is a new request */ |
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ino = autofs_dentry_ino(dentry); |
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if (!ino) |
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return 1; |
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/* |
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* If we've been asked to wait on an existing expire (NFY_NONE) |
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* but there is no wait in the queue ... |
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*/ |
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if (notify == NFY_NONE) { |
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/* |
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* Either we've betean the pending expire to post it's |
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* wait or it finished while we waited on the mutex. |
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* So we need to wait till either, the wait appears |
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* or the expire finishes. |
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*/ |
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while (ino->flags & AUTOFS_INF_EXPIRING) { |
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mutex_unlock(&sbi->wq_mutex); |
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schedule_timeout_interruptible(HZ/10); |
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if (mutex_lock_interruptible(&sbi->wq_mutex)) |
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return -EINTR; |
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if (sbi->flags & AUTOFS_SBI_CATATONIC) |
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return -ENOENT; |
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wq = autofs_find_wait(sbi, qstr); |
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if (wq) { |
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*wait = wq; |
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return 1; |
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} |
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} |
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/* |
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* Not ideal but the status has already gone. Of the two |
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* cases where we wait on NFY_NONE neither depend on the |
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* return status of the wait. |
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*/ |
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return 0; |
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} |
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/* |
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* If we've been asked to trigger a mount and the request |
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* completed while we waited on the mutex ... |
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*/ |
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if (notify == NFY_MOUNT) { |
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struct dentry *new = NULL; |
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struct path this; |
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int valid = 1; |
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/* |
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* If the dentry was successfully mounted while we slept |
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* on the wait queue mutex we can return success. If it |
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* isn't mounted (doesn't have submounts for the case of |
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* a multi-mount with no mount at it's base) we can |
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* continue on and create a new request. |
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*/ |
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if (!IS_ROOT(dentry)) { |
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if (d_unhashed(dentry) && |
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d_really_is_positive(dentry)) { |
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struct dentry *parent = dentry->d_parent; |
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new = d_lookup(parent, &dentry->d_name); |
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if (new) |
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dentry = new; |
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} |
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} |
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this.mnt = path->mnt; |
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this.dentry = dentry; |
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if (path_has_submounts(&this)) |
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valid = 0; |
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if (new) |
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dput(new); |
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return valid; |
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} |
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return 1; |
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} |
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int autofs_wait(struct autofs_sb_info *sbi, |
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const struct path *path, enum autofs_notify notify) |
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{ |
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struct dentry *dentry = path->dentry; |
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struct autofs_wait_queue *wq; |
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struct qstr qstr; |
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char *name; |
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int status, ret, type; |
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unsigned int offset = 0; |
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pid_t pid; |
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pid_t tgid; |
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/* In catatonic mode, we don't wait for nobody */ |
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if (sbi->flags & AUTOFS_SBI_CATATONIC) |
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return -ENOENT; |
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/* |
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* Try translating pids to the namespace of the daemon. |
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* |
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* Zero means failure: we are in an unrelated pid namespace. |
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*/ |
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pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp)); |
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tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp)); |
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if (pid == 0 || tgid == 0) |
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return -ENOENT; |
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if (d_really_is_negative(dentry)) { |
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/* |
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* A wait for a negative dentry is invalid for certain |
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* cases. A direct or offset mount "always" has its mount |
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* point directory created and so the request dentry must |
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* be positive or the map key doesn't exist. The situation |
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* is very similar for indirect mounts except only dentrys |
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* in the root of the autofs file system may be negative. |
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*/ |
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if (autofs_type_trigger(sbi->type)) |
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return -ENOENT; |
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else if (!IS_ROOT(dentry->d_parent)) |
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return -ENOENT; |
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} |
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name = kmalloc(NAME_MAX + 1, GFP_KERNEL); |
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if (!name) |
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return -ENOMEM; |
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/* If this is a direct mount request create a dummy name */ |
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if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) { |
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qstr.name = name; |
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qstr.len = sprintf(name, "%p", dentry); |
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} else { |
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char *p = dentry_path_raw(dentry, name, NAME_MAX); |
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if (IS_ERR(p)) { |
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kfree(name); |
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return -ENOENT; |
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} |
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qstr.name = ++p; // skip the leading slash |
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qstr.len = strlen(p); |
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offset = p - name; |
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} |
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qstr.hash = full_name_hash(dentry, name, qstr.len); |
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if (mutex_lock_interruptible(&sbi->wq_mutex)) { |
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kfree(name); |
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return -EINTR; |
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} |
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ret = validate_request(&wq, sbi, &qstr, path, notify); |
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if (ret <= 0) { |
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if (ret != -EINTR) |
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mutex_unlock(&sbi->wq_mutex); |
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kfree(name); |
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return ret; |
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} |
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if (!wq) { |
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/* Create a new wait queue */ |
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wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL); |
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if (!wq) { |
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kfree(name); |
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mutex_unlock(&sbi->wq_mutex); |
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return -ENOMEM; |
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} |
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wq->wait_queue_token = autofs_next_wait_queue; |
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if (++autofs_next_wait_queue == 0) |
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autofs_next_wait_queue = 1; |
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wq->next = sbi->queues; |
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sbi->queues = wq; |
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init_waitqueue_head(&wq->queue); |
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memcpy(&wq->name, &qstr, sizeof(struct qstr)); |
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wq->offset = offset; |
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wq->dev = autofs_get_dev(sbi); |
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wq->ino = autofs_get_ino(sbi); |
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wq->uid = current_uid(); |
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wq->gid = current_gid(); |
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wq->pid = pid; |
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wq->tgid = tgid; |
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wq->status = -EINTR; /* Status return if interrupted */ |
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wq->wait_ctr = 2; |
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if (sbi->version < 5) { |
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if (notify == NFY_MOUNT) |
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type = autofs_ptype_missing; |
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else |
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type = autofs_ptype_expire_multi; |
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} else { |
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if (notify == NFY_MOUNT) |
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type = autofs_type_trigger(sbi->type) ? |
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autofs_ptype_missing_direct : |
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autofs_ptype_missing_indirect; |
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else |
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type = autofs_type_trigger(sbi->type) ? |
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autofs_ptype_expire_direct : |
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autofs_ptype_expire_indirect; |
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} |
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pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n", |
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(unsigned long) wq->wait_queue_token, wq->name.len, |
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wq->name.name, notify); |
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/* |
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* autofs_notify_daemon() may block; it will unlock ->wq_mutex |
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*/ |
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autofs_notify_daemon(sbi, wq, type); |
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} else { |
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wq->wait_ctr++; |
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pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n", |
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(unsigned long) wq->wait_queue_token, wq->name.len, |
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wq->name.name, notify); |
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mutex_unlock(&sbi->wq_mutex); |
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kfree(name); |
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} |
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/* |
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* wq->name.name is NULL iff the lock is already released |
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* or the mount has been made catatonic. |
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*/ |
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wait_event_killable(wq->queue, wq->name.name == NULL); |
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status = wq->status; |
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/* |
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* For direct and offset mounts we need to track the requester's |
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* uid and gid in the dentry info struct. This is so it can be |
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* supplied, on request, by the misc device ioctl interface. |
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* This is needed during daemon resatart when reconnecting |
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* to existing, active, autofs mounts. The uid and gid (and |
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* related string values) may be used for macro substitution |
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* in autofs mount maps. |
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*/ |
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if (!status) { |
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struct autofs_info *ino; |
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struct dentry *de = NULL; |
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/* direct mount or browsable map */ |
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ino = autofs_dentry_ino(dentry); |
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if (!ino) { |
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/* If not lookup actual dentry used */ |
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de = d_lookup(dentry->d_parent, &dentry->d_name); |
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if (de) |
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ino = autofs_dentry_ino(de); |
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} |
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/* Set mount requester */ |
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if (ino) { |
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spin_lock(&sbi->fs_lock); |
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ino->uid = wq->uid; |
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ino->gid = wq->gid; |
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spin_unlock(&sbi->fs_lock); |
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} |
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if (de) |
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dput(de); |
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} |
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/* Are we the last process to need status? */ |
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mutex_lock(&sbi->wq_mutex); |
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if (!--wq->wait_ctr) |
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kfree(wq); |
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mutex_unlock(&sbi->wq_mutex); |
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return status; |
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} |
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int autofs_wait_release(struct autofs_sb_info *sbi, |
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autofs_wqt_t wait_queue_token, int status) |
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{ |
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struct autofs_wait_queue *wq, **wql; |
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mutex_lock(&sbi->wq_mutex); |
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for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) { |
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if (wq->wait_queue_token == wait_queue_token) |
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break; |
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} |
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if (!wq) { |
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mutex_unlock(&sbi->wq_mutex); |
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return -EINVAL; |
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} |
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*wql = wq->next; /* Unlink from chain */ |
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kfree(wq->name.name - wq->offset); |
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wq->name.name = NULL; /* Do not wait on this queue */ |
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wq->status = status; |
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wake_up(&wq->queue); |
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if (!--wq->wait_ctr) |
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kfree(wq); |
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mutex_unlock(&sbi->wq_mutex); |
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return 0; |
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}
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