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Date: Mon, 13 Jun 2016 22:45:05 +0900
From: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-nilfs <linux-nilfs@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Subject: [PATCH 1/3] nilfs2: fix misuse of a semaphore in sysfs code
Variables ns_seg_seq, ns_segnum, ns_nextnum, ns_pseg_offset, ns_cno,
ns_ctime, ns_nongc_ctime, and ns_ndirtyblks, are protected by
ns_segctor_sem, but ns_sem is wrongly used by the nilfs sysfs code
when reading these variables. This fixes the misuse and clarifies
which semaphore protects them in the comment of the_nilfs struct.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
---
fs/nilfs2/sysfs.c | 44 ++++++++++++++++++++++----------------------
fs/nilfs2/the_nilfs.h | 7 ++-----
2 files changed, 24 insertions(+), 27 deletions(-)
diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 8e57bb9..490303e 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -326,9 +326,9 @@ nilfs_checkpoints_next_checkpoint_show(struct nilfs_checkpoints_attr *attr,
{
__u64 cno;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
cno = nilfs->ns_cno;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n", cno);
}
@@ -511,9 +511,9 @@ nilfs_segctor_current_seg_sequence_show(struct nilfs_segctor_attr *attr,
{
u64 seg_seq;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
seg_seq = nilfs->ns_seg_seq;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n", seg_seq);
}
@@ -525,9 +525,9 @@ nilfs_segctor_current_last_full_seg_show(struct nilfs_segctor_attr *attr,
{
__u64 segnum;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
segnum = nilfs->ns_segnum;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n", segnum);
}
@@ -539,9 +539,9 @@ nilfs_segctor_next_full_seg_show(struct nilfs_segctor_attr *attr,
{
__u64 nextnum;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
nextnum = nilfs->ns_nextnum;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n", nextnum);
}
@@ -553,9 +553,9 @@ nilfs_segctor_next_pseg_offset_show(struct nilfs_segctor_attr *attr,
{
unsigned long pseg_offset;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
pseg_offset = nilfs->ns_pseg_offset;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%lu\n", pseg_offset);
}
@@ -567,9 +567,9 @@ nilfs_segctor_next_checkpoint_show(struct nilfs_segctor_attr *attr,
{
__u64 cno;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
cno = nilfs->ns_cno;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n", cno);
}
@@ -581,9 +581,9 @@ nilfs_segctor_last_seg_write_time_show(struct nilfs_segctor_attr *attr,
{
time_t ctime;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
ctime = nilfs->ns_ctime;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return NILFS_SHOW_TIME(ctime, buf);
}
@@ -595,9 +595,9 @@ nilfs_segctor_last_seg_write_time_secs_show(struct nilfs_segctor_attr *attr,
{
time_t ctime;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
ctime = nilfs->ns_ctime;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n", (unsigned long long)ctime);
}
@@ -609,9 +609,9 @@ nilfs_segctor_last_nongc_write_time_show(struct nilfs_segctor_attr *attr,
{
time_t nongc_ctime;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
nongc_ctime = nilfs->ns_nongc_ctime;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return NILFS_SHOW_TIME(nongc_ctime, buf);
}
@@ -623,9 +623,9 @@ nilfs_segctor_last_nongc_write_time_secs_show(struct nilfs_segctor_attr *attr,
{
time_t nongc_ctime;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
nongc_ctime = nilfs->ns_nongc_ctime;
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%llu\n",
(unsigned long long)nongc_ctime);
@@ -638,9 +638,9 @@ nilfs_segctor_dirty_data_blocks_count_show(struct nilfs_segctor_attr *attr,
{
u32 ndirtyblks;
- down_read(&nilfs->ns_sem);
+ down_read(&nilfs->ns_segctor_sem);
ndirtyblks = atomic_read(&nilfs->ns_ndirtyblks);
- up_read(&nilfs->ns_sem);
+ up_read(&nilfs->ns_segctor_sem);
return snprintf(buf, PAGE_SIZE, "%u\n", ndirtyblks);
}
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 79d1421..b305c6f 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -122,11 +122,8 @@ struct the_nilfs {
unsigned int ns_sb_update_freq;
/*
- * Following fields are dedicated to a writable FS-instance.
- * Except for the period seeking checkpoint, code outside the segment
- * constructor must lock a segment semaphore while accessing these
- * fields.
- * The writable FS-instance is sole during a lifetime of the_nilfs.
+ * The following fields are updated by a writable FS-instance.
+ * These fields are protected by ns_segctor_sem outside load_nilfs().
*/
u64 ns_seg_seq;
__u64 ns_segnum;
--
1.8.3.1
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