From b4c20166dcfca106f0f416bfce200099ed76ab18 Mon Sep 17 00:00:00 2001 From: Abhijith Das Date: Thu, 13 Sep 2007 23:35:27 -0500 Subject: [PATCH] [GFS2] flocks from same process trip kernel BUG at fs/gfs2/glock.c:1118! This patch adds a new flag to the gfs2_holder structure GL_FLOCK. It is set on holders of glocks representing flocks. This flag is checked in add_to_queue() and a process is permitted to queue more than one holder onto a glock if it is set. This solves the issue of a process not being able to do multiple flocks on the same file. Through a single descriptor, a process can now promote and demote flocks. Through multiple descriptors a process can now queue multiple flocks on the same file. There's still the problem of a process deadlocking itself (because gfs2 blocking locks are not interruptible) by queueing incompatible deadlock. Signed-off-by: Abhijith Das Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 43 +++++++++++++++++++++++++------------------ fs/gfs2/glock.h | 1 + fs/gfs2/ops_file.c | 13 ++++++------- 3 files changed, 32 insertions(+), 25 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 931368a385c8..d631cad0aeee 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1106,24 +1106,31 @@ static void add_to_queue(struct gfs2_holder *gh) if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags)) BUG(); - existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner_pid); - if (existing) { - print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip); - printk(KERN_INFO "pid : %d\n", existing->gh_owner_pid); - printk(KERN_INFO "lock type : %d lock state : %d\n", - existing->gh_gl->gl_name.ln_type, existing->gh_gl->gl_state); - print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip); - printk(KERN_INFO "pid : %d\n", gh->gh_owner_pid); - printk(KERN_INFO "lock type : %d lock state : %d\n", - gl->gl_name.ln_type, gl->gl_state); - BUG(); - } - - existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner_pid); - if (existing) { - print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip); - print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip); - BUG(); + if (!(gh->gh_flags & GL_FLOCK)) { + existing = find_holder_by_owner(&gl->gl_holders, + gh->gh_owner_pid); + if (existing) { + print_symbol(KERN_WARNING "original: %s\n", + existing->gh_ip); + printk(KERN_INFO "pid : %d\n", existing->gh_owner_pid); + printk(KERN_INFO "lock type : %d lock state : %d\n", + existing->gh_gl->gl_name.ln_type, + existing->gh_gl->gl_state); + print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip); + printk(KERN_INFO "pid : %d\n", gh->gh_owner_pid); + printk(KERN_INFO "lock type : %d lock state : %d\n", + gl->gl_name.ln_type, gl->gl_state); + BUG(); + } + + existing = find_holder_by_owner(&gl->gl_waiters3, + gh->gh_owner_pid); + if (existing) { + print_symbol(KERN_WARNING "original: %s\n", + existing->gh_ip); + print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip); + BUG(); + } } if (gh->gh_flags & LM_FLAG_PRIORITY) diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h index f7a8e626aa08..b16f604eea9f 100644 --- a/fs/gfs2/glock.h +++ b/fs/gfs2/glock.h @@ -26,6 +26,7 @@ #define GL_SKIP 0x00000100 #define GL_ATIME 0x00000200 #define GL_NOCACHE 0x00000400 +#define GL_FLOCK 0x00000800 #define GL_NOCANCEL 0x00001000 #define GLR_TRYFAILED 13 diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c index 94d76ace0b95..46a9e10ff17b 100644 --- a/fs/gfs2/ops_file.c +++ b/fs/gfs2/ops_file.c @@ -571,7 +571,8 @@ static int do_flock(struct file *file, int cmd, struct file_lock *fl) int error = 0; state = (fl->fl_type == F_WRLCK) ? LM_ST_EXCLUSIVE : LM_ST_SHARED; - flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE; + flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE + | GL_FLOCK; mutex_lock(&fp->f_fl_mutex); @@ -579,21 +580,19 @@ static int do_flock(struct file *file, int cmd, struct file_lock *fl) if (gl) { if (fl_gh->gh_state == state) goto out; - gfs2_glock_hold(gl); flock_lock_file_wait(file, &(struct file_lock){.fl_type = F_UNLCK}); - gfs2_glock_dq_uninit(fl_gh); + gfs2_glock_dq_wait(fl_gh); + gfs2_holder_reinit(state, flags, fl_gh); } else { error = gfs2_glock_get(GFS2_SB(&ip->i_inode), ip->i_no_addr, &gfs2_flock_glops, CREATE, &gl); if (error) goto out; + gfs2_holder_init(gl, state, flags, fl_gh); + gfs2_glock_put(gl); } - - gfs2_holder_init(gl, state, flags, fl_gh); - gfs2_glock_put(gl); - error = gfs2_glock_nq(fl_gh); if (error) { gfs2_holder_uninit(fl_gh); -- 2.39.5