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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.

Link: http://lkml.kernel.org/r/1465825507-3407-2-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ryusuke Konishi 2016-08-02 14:05:25 -07:00 committed by Linus Torvalds
parent a7d3f104da
commit ad980c9ab7
2 changed files with 24 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
fs/nilfs2/sysfs.c
View File

@ -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);
}

7
fs/nilfs2/the_nilfs.h
View File

@ -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;