This is a note to let you know that I've just added the patch titled gfs2: Fix debugfs glocks dump to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: gfs2-fix-debugfs-glocks-dump.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 10201655b085df8e000822e496e5d4016a167a36 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Date: Tue, 19 Sep 2017 07:15:35 -0500 Subject: gfs2: Fix debugfs glocks dump From: Andreas Gruenbacher <agruenba@xxxxxxxxxx> commit 10201655b085df8e000822e496e5d4016a167a36 upstream. The switch to rhashtables (commit 88ffbf3e03) broke the debugfs glock dump (/sys/kernel/debug/gfs2/<device>/glocks) for dumps bigger than a single buffer: the right function for restarting an rhashtable iteration from the beginning of the hash table is rhashtable_walk_enter; rhashtable_walk_stop + rhashtable_walk_start will just resume from the current position. The upstream commit doesn't directly apply to 4.4.y because 4.4.y doesn't have rhashtable_walk_enter and the following mainline commits: 92ecd73a887c4a2b94daf5fc35179d75d1c4ef95 gfs2: Deduplicate gfs2_{glocks,glstats}_open cc37a62785a584f4875788689f3fd1fa6e4eb291 gfs2: Replace rhashtable_walk_init with rhashtable_walk_enter Other than rhashtable_walk_enter, rhashtable_walk_init can fail. To handle the failure case in gfs2_glock_seq_stop, we check if rhashtable_walk_init has initialized iter->walker; if it has not, we must not call rhashtable_walk_stop or rhashtable_walk_exit. Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/gfs2/glock.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1814,13 +1814,10 @@ static void *gfs2_glock_seq_start(struct { struct gfs2_glock_iter *gi = seq->private; loff_t n = *pos; - int ret; - if (gi->last_pos <= *pos) - n = (*pos - gi->last_pos); - - ret = rhashtable_walk_start(&gi->hti); - if (ret) + if (rhashtable_walk_init(&gl_hash_table, &gi->hti) != 0) + return NULL; + if (rhashtable_walk_start(&gi->hti) != 0) return NULL; do { @@ -1828,6 +1825,7 @@ static void *gfs2_glock_seq_start(struct } while (gi->gl && n--); gi->last_pos = *pos; + return gi->gl; } @@ -1839,6 +1837,7 @@ static void *gfs2_glock_seq_next(struct (*pos)++; gi->last_pos = *pos; gfs2_glock_iter_next(gi); + return gi->gl; } @@ -1847,7 +1846,10 @@ static void gfs2_glock_seq_stop(struct s struct gfs2_glock_iter *gi = seq->private; gi->gl = NULL; - rhashtable_walk_stop(&gi->hti); + if (gi->hti.walker) { + rhashtable_walk_stop(&gi->hti); + rhashtable_walk_exit(&gi->hti); + } } static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr) @@ -1910,12 +1912,10 @@ static int gfs2_glocks_open(struct inode struct gfs2_glock_iter *gi = seq->private; gi->sdp = inode->i_private; - gi->last_pos = 0; seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN); if (seq->buf) seq->size = GFS2_SEQ_GOODSIZE; gi->gl = NULL; - ret = rhashtable_walk_init(&gl_hash_table, &gi->hti); } return ret; } @@ -1926,7 +1926,6 @@ static int gfs2_glocks_release(struct in struct gfs2_glock_iter *gi = seq->private; gi->gl = NULL; - rhashtable_walk_exit(&gi->hti); return seq_release_private(inode, file); } @@ -1938,12 +1937,10 @@ static int gfs2_glstats_open(struct inod struct seq_file *seq = file->private_data; struct gfs2_glock_iter *gi = seq->private; gi->sdp = inode->i_private; - gi->last_pos = 0; seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN); if (seq->buf) seq->size = GFS2_SEQ_GOODSIZE; gi->gl = NULL; - ret = rhashtable_walk_init(&gl_hash_table, &gi->hti); } return ret; } Patches currently in stable-queue which might be from agruenba@xxxxxxxxxx are queue-4.4/gfs2-fix-debugfs-glocks-dump.patch queue-4.4/vfs-return-enxio-for-negative-seek_hole-seek_data-offsets.patch