From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxx Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/nilfs2/sysfs.c | 44 ++++++++++++++++++++-------------------- fs/nilfs2/the_nilfs.h | 7 +----- 2 files changed, 24 insertions(+), 27 deletions(-) diff -puN fs/nilfs2/sysfs.c~nilfs2-fix-misuse-of-a-semaphore-in-sysfs-code fs/nilfs2/sysfs.c --- a/fs/nilfs2/sysfs.c~nilfs2-fix-misuse-of-a-semaphore-in-sysfs-code +++ a/fs/nilfs2/sysfs.c @@ -326,9 +326,9 @@ nilfs_checkpoints_next_checkpoint_show(s { __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( { 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 { __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 { __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(stru { 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(struc { __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(s { 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_s { 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 { 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 { 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_sh { 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 -puN fs/nilfs2/the_nilfs.h~nilfs2-fix-misuse-of-a-semaphore-in-sysfs-code fs/nilfs2/the_nilfs.h --- a/fs/nilfs2/the_nilfs.h~nilfs2-fix-misuse-of-a-semaphore-in-sysfs-code +++ a/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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
