autofs4: deal with autofs4_write/autofs4_write races

[mirror_ubuntu-zesty-kernel.git] / fs / autofs4 / waitq.c

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index e1fbdeef85db2e4b73e78eaf6266d2784e2385b0..9ef5b2914407c40327db81a5688850a808210991 100644 (file)
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -56,26 +56,27 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
        mutex_unlock(&sbi->wq_mutex);
 }
 
-static int autofs4_write(struct file *file, const void *addr, int bytes)
+static int autofs4_write(struct autofs_sb_info *sbi,
+                        struct file *file, const void *addr, int bytes)
 {
        unsigned long sigpipe, flags;
        mm_segment_t fs;
        const char *data = (const char *)addr;
        ssize_t wr = 0;
 
-       /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
-
        sigpipe = sigismember(&current->pending.signal, SIGPIPE);
 
        /* Save pointer to user space and point back to kernel space */
        fs = get_fs();
        set_fs(KERNEL_DS);
 
+       mutex_lock(&sbi->pipe_mutex);
        while (bytes &&
               (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
                data += wr;
                bytes -= wr;
        }
+       mutex_lock(&sbi->pipe_mutex);
 
        set_fs(fs);
 
@@ -110,6 +111,13 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
 
        pkt.hdr.proto_version = sbi->version;
        pkt.hdr.type = type;
+       mutex_lock(&sbi->wq_mutex);
+
+       /* Check if we have become catatonic */
+       if (sbi->catatonic) {
+               mutex_unlock(&sbi->wq_mutex);
+               return;
+       }
        switch (type) {
        /* Kernel protocol v4 missing and expire packets */
        case autofs_ptype_missing:
@@ -163,22 +171,18 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
        }
        default:
                printk("autofs4_notify_daemon: bad type %d!\n", type);
+               mutex_unlock(&sbi->wq_mutex);
                return;
        }
 
-       /* Check if we have become catatonic */
-       mutex_lock(&sbi->wq_mutex);
-       if (!sbi->catatonic) {
-               pipe = sbi->pipe;
-               get_file(pipe);
-       }
+       pipe = sbi->pipe;
+       get_file(pipe);
+
        mutex_unlock(&sbi->wq_mutex);
 
-       if (pipe) {
-               if (autofs4_write(pipe, &pkt, pktsz))
-                       autofs4_catatonic_mode(sbi);
-               fput(pipe);
-       }
+       if (autofs4_write(sbi, pipe, &pkt, pktsz))
+               autofs4_catatonic_mode(sbi);
+       fput(pipe);
 }
 
 static int autofs4_getpath(struct autofs_sb_info *sbi,
@@ -257,6 +261,9 @@ static int validate_request(struct autofs_wait_queue **wait,
        struct autofs_wait_queue *wq;
        struct autofs_info *ino;
 
+       if (sbi->catatonic)
+               return -ENOENT;
+
        /* Wait in progress, continue; */
        wq = autofs4_find_wait(sbi, qstr);
        if (wq) {
@@ -289,6 +296,9 @@ static int validate_request(struct autofs_wait_queue **wait,
                        if (mutex_lock_interruptible(&sbi->wq_mutex))
                                return -EINTR;
 
+                       if (sbi->catatonic)
+                               return -ENOENT;
+
                        wq = autofs4_find_wait(sbi, qstr);
                        if (wq) {
                                *wait = wq;
@@ -389,7 +399,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 
        ret = validate_request(&wq, sbi, &qstr, dentry, notify);
        if (ret <= 0) {
-               if (ret == 0)
+               if (ret != -EINTR)
                        mutex_unlock(&sbi->wq_mutex);
                kfree(qstr.name);
                return ret;