![Jean Delvare](/assets/img/avatar_default.png)
bdevname() fills the buffer that it is given as a parameter, so calling strcpy() or snprintf() on the returned value is redundant (and probably not guaranteed to work - I don't think strcpy and snprintf support overlapping buffers.) Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Stephen Tweedie <sct@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
511 lines
11 KiB
C
511 lines
11 KiB
C
/*
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* Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#include <linux/kernel.h>
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#include <linux/blkdev.h>
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#include <linux/blktrace_api.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/mutex.h>
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#include <linux/debugfs.h>
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#include <linux/time.h>
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#include <asm/uaccess.h>
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static unsigned int blktrace_seq __read_mostly = 1;
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/*
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* Send out a notify message.
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*/
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static void trace_note(struct blk_trace *bt, pid_t pid, int action,
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const void *data, size_t len)
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{
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struct blk_io_trace *t;
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t = relay_reserve(bt->rchan, sizeof(*t) + len);
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if (t) {
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const int cpu = smp_processor_id();
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t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
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t->time = ktime_to_ns(ktime_get());
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t->device = bt->dev;
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t->action = action;
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t->pid = pid;
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t->cpu = cpu;
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t->pdu_len = len;
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memcpy((void *) t + sizeof(*t), data, len);
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}
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}
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/*
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* Send out a notify for this process, if we haven't done so since a trace
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* started
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*/
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static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
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{
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tsk->btrace_seq = blktrace_seq;
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trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
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}
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static void trace_note_time(struct blk_trace *bt)
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{
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struct timespec now;
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unsigned long flags;
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u32 words[2];
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getnstimeofday(&now);
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words[0] = now.tv_sec;
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words[1] = now.tv_nsec;
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local_irq_save(flags);
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trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
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local_irq_restore(flags);
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}
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static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
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pid_t pid)
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{
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if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
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return 1;
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if (sector < bt->start_lba || sector > bt->end_lba)
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return 1;
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if (bt->pid && pid != bt->pid)
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return 1;
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return 0;
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}
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/*
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* Data direction bit lookup
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*/
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static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) };
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/*
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* Bio action bits of interest
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*/
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static u32 bio_act[9] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD), 0, 0, 0, BLK_TC_ACT(BLK_TC_META) };
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/*
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* More could be added as needed, taking care to increment the decrementer
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* to get correct indexing
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*/
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#define trace_barrier_bit(rw) \
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(((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))
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#define trace_sync_bit(rw) \
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(((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))
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#define trace_ahead_bit(rw) \
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(((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))
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#define trace_meta_bit(rw) \
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(((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3))
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/*
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* The worker for the various blk_add_trace*() types. Fills out a
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* blk_io_trace structure and places it in a per-cpu subbuffer.
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*/
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void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
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int rw, u32 what, int error, int pdu_len, void *pdu_data)
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{
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struct task_struct *tsk = current;
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struct blk_io_trace *t;
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unsigned long flags;
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unsigned long *sequence;
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pid_t pid;
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int cpu;
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if (unlikely(bt->trace_state != Blktrace_running))
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return;
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what |= ddir_act[rw & WRITE];
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what |= bio_act[trace_barrier_bit(rw)];
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what |= bio_act[trace_sync_bit(rw)];
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what |= bio_act[trace_ahead_bit(rw)];
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what |= bio_act[trace_meta_bit(rw)];
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pid = tsk->pid;
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if (unlikely(act_log_check(bt, what, sector, pid)))
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return;
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/*
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* A word about the locking here - we disable interrupts to reserve
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* some space in the relay per-cpu buffer, to prevent an irq
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* from coming in and stepping on our toes. Once reserved, it's
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* enough to get preemption disabled to prevent read of this data
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* before we are through filling it. get_cpu()/put_cpu() does this
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* for us
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*/
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local_irq_save(flags);
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if (unlikely(tsk->btrace_seq != blktrace_seq))
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trace_note_tsk(bt, tsk);
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t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
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if (t) {
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cpu = smp_processor_id();
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sequence = per_cpu_ptr(bt->sequence, cpu);
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t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
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t->sequence = ++(*sequence);
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t->time = ktime_to_ns(ktime_get());
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t->sector = sector;
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t->bytes = bytes;
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t->action = what;
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t->pid = pid;
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t->device = bt->dev;
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t->cpu = cpu;
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t->error = error;
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t->pdu_len = pdu_len;
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if (pdu_len)
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memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
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}
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local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(__blk_add_trace);
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static struct dentry *blk_tree_root;
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static DEFINE_MUTEX(blk_tree_mutex);
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static unsigned int root_users;
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static inline void blk_remove_root(void)
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{
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if (blk_tree_root) {
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debugfs_remove(blk_tree_root);
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blk_tree_root = NULL;
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}
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}
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static void blk_remove_tree(struct dentry *dir)
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{
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mutex_lock(&blk_tree_mutex);
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debugfs_remove(dir);
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if (--root_users == 0)
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blk_remove_root();
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mutex_unlock(&blk_tree_mutex);
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}
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static struct dentry *blk_create_tree(const char *blk_name)
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{
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struct dentry *dir = NULL;
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int created = 0;
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mutex_lock(&blk_tree_mutex);
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if (!blk_tree_root) {
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blk_tree_root = debugfs_create_dir("block", NULL);
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if (!blk_tree_root)
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goto err;
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created = 1;
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}
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dir = debugfs_create_dir(blk_name, blk_tree_root);
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if (dir)
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root_users++;
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else {
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/* Delete root only if we created it */
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if (created)
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blk_remove_root();
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}
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err:
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mutex_unlock(&blk_tree_mutex);
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return dir;
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}
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static void blk_trace_cleanup(struct blk_trace *bt)
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{
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relay_close(bt->rchan);
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debugfs_remove(bt->dropped_file);
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blk_remove_tree(bt->dir);
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free_percpu(bt->sequence);
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kfree(bt);
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}
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int blk_trace_remove(struct request_queue *q)
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{
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struct blk_trace *bt;
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bt = xchg(&q->blk_trace, NULL);
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if (!bt)
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return -EINVAL;
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if (bt->trace_state == Blktrace_setup ||
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bt->trace_state == Blktrace_stopped)
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blk_trace_cleanup(bt);
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return 0;
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}
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EXPORT_SYMBOL_GPL(blk_trace_remove);
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static int blk_dropped_open(struct inode *inode, struct file *filp)
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{
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filp->private_data = inode->i_private;
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return 0;
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}
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static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
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size_t count, loff_t *ppos)
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{
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struct blk_trace *bt = filp->private_data;
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char buf[16];
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snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
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return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
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}
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static const struct file_operations blk_dropped_fops = {
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.owner = THIS_MODULE,
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.open = blk_dropped_open,
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.read = blk_dropped_read,
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};
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/*
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* Keep track of how many times we encountered a full subbuffer, to aid
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* the user space app in telling how many lost events there were.
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*/
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static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
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void *prev_subbuf, size_t prev_padding)
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{
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struct blk_trace *bt;
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if (!relay_buf_full(buf))
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return 1;
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bt = buf->chan->private_data;
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atomic_inc(&bt->dropped);
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return 0;
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}
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static int blk_remove_buf_file_callback(struct dentry *dentry)
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{
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debugfs_remove(dentry);
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return 0;
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}
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static struct dentry *blk_create_buf_file_callback(const char *filename,
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struct dentry *parent,
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int mode,
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struct rchan_buf *buf,
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int *is_global)
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{
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return debugfs_create_file(filename, mode, parent, buf,
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&relay_file_operations);
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}
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static struct rchan_callbacks blk_relay_callbacks = {
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.subbuf_start = blk_subbuf_start_callback,
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.create_buf_file = blk_create_buf_file_callback,
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.remove_buf_file = blk_remove_buf_file_callback,
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};
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/*
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* Setup everything required to start tracing
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*/
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int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
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struct blk_user_trace_setup *buts)
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{
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struct blk_trace *old_bt, *bt = NULL;
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struct dentry *dir = NULL;
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int ret, i;
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if (!buts->buf_size || !buts->buf_nr)
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return -EINVAL;
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strcpy(buts->name, name);
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/*
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* some device names have larger paths - convert the slashes
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* to underscores for this to work as expected
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*/
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for (i = 0; i < strlen(buts->name); i++)
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if (buts->name[i] == '/')
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buts->name[i] = '_';
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ret = -ENOMEM;
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bt = kzalloc(sizeof(*bt), GFP_KERNEL);
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if (!bt)
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goto err;
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bt->sequence = alloc_percpu(unsigned long);
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if (!bt->sequence)
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goto err;
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ret = -ENOENT;
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dir = blk_create_tree(buts->name);
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if (!dir)
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goto err;
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bt->dir = dir;
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bt->dev = dev;
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atomic_set(&bt->dropped, 0);
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ret = -EIO;
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bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
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if (!bt->dropped_file)
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goto err;
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bt->rchan = relay_open("trace", dir, buts->buf_size,
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buts->buf_nr, &blk_relay_callbacks, bt);
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if (!bt->rchan)
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goto err;
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bt->act_mask = buts->act_mask;
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if (!bt->act_mask)
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bt->act_mask = (u16) -1;
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bt->start_lba = buts->start_lba;
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bt->end_lba = buts->end_lba;
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if (!bt->end_lba)
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bt->end_lba = -1ULL;
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bt->pid = buts->pid;
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bt->trace_state = Blktrace_setup;
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ret = -EBUSY;
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old_bt = xchg(&q->blk_trace, bt);
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if (old_bt) {
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(void) xchg(&q->blk_trace, old_bt);
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goto err;
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}
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return 0;
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err:
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if (dir)
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blk_remove_tree(dir);
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if (bt) {
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if (bt->dropped_file)
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debugfs_remove(bt->dropped_file);
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free_percpu(bt->sequence);
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if (bt->rchan)
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relay_close(bt->rchan);
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kfree(bt);
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}
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return ret;
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}
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int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
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char __user *arg)
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{
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struct blk_user_trace_setup buts;
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int ret;
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ret = copy_from_user(&buts, arg, sizeof(buts));
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if (ret)
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return -EFAULT;
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ret = do_blk_trace_setup(q, name, dev, &buts);
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if (ret)
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return ret;
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if (copy_to_user(arg, &buts, sizeof(buts)))
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return -EFAULT;
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return 0;
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}
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EXPORT_SYMBOL_GPL(blk_trace_setup);
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int blk_trace_startstop(struct request_queue *q, int start)
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{
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struct blk_trace *bt;
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int ret;
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if ((bt = q->blk_trace) == NULL)
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return -EINVAL;
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/*
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* For starting a trace, we can transition from a setup or stopped
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* trace. For stopping a trace, the state must be running
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*/
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ret = -EINVAL;
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if (start) {
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if (bt->trace_state == Blktrace_setup ||
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bt->trace_state == Blktrace_stopped) {
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blktrace_seq++;
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smp_mb();
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bt->trace_state = Blktrace_running;
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trace_note_time(bt);
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ret = 0;
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}
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} else {
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if (bt->trace_state == Blktrace_running) {
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bt->trace_state = Blktrace_stopped;
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relay_flush(bt->rchan);
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ret = 0;
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}
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(blk_trace_startstop);
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/**
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* blk_trace_ioctl: - handle the ioctls associated with tracing
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* @bdev: the block device
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* @cmd: the ioctl cmd
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* @arg: the argument data, if any
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*
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**/
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int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
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{
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struct request_queue *q;
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int ret, start = 0;
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char b[BDEVNAME_SIZE];
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q = bdev_get_queue(bdev);
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if (!q)
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return -ENXIO;
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mutex_lock(&bdev->bd_mutex);
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switch (cmd) {
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case BLKTRACESETUP:
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bdevname(bdev, b);
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ret = blk_trace_setup(q, b, bdev->bd_dev, arg);
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break;
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case BLKTRACESTART:
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start = 1;
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case BLKTRACESTOP:
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ret = blk_trace_startstop(q, start);
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break;
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case BLKTRACETEARDOWN:
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ret = blk_trace_remove(q);
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break;
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default:
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ret = -ENOTTY;
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break;
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}
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mutex_unlock(&bdev->bd_mutex);
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return ret;
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}
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/**
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* blk_trace_shutdown: - stop and cleanup trace structures
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* @q: the request queue associated with the device
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*
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**/
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void blk_trace_shutdown(struct request_queue *q)
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{
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if (q->blk_trace) {
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blk_trace_startstop(q, 0);
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blk_trace_remove(q);
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}
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}
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