| Message ID | 685386c2840b76c49b060bf7dcea1fefacf18176.1614322182.git.luolongjun@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] fs/locks: print full locks information | expand |
On Thu, 2021-02-25 at 22:58 -0500, Luo Longjun wrote: > Commit fd7732e033e3 ("fs/locks: create a tree of dependent requests.") > has put blocked locks into a tree. > > So, with a for loop, we can't check all locks information. > > To solve this problem, we should traverse the tree. > > Signed-off-by: Luo Longjun <luolongjun@huawei.com> > --- > fs/locks.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 56 insertions(+), 9 deletions(-) > > diff --git a/fs/locks.c b/fs/locks.c > index 99ca97e81b7a..ecaecd1f1b58 100644 > --- a/fs/locks.c > +++ b/fs/locks.c > @@ -2828,7 +2828,7 @@ struct locks_iterator { > }; > > > > > static void lock_get_status(struct seq_file *f, struct file_lock *fl, > - loff_t id, char *pfx) > + loff_t id, char *pfx, int repeat) > { > struct inode *inode = NULL; > unsigned int fl_pid; > @@ -2844,7 +2844,11 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, > if (fl->fl_file != NULL) > inode = locks_inode(fl->fl_file); > > > > > - seq_printf(f, "%lld:%s ", id, pfx); > + seq_printf(f, "%lld: ", id); > + > + if (repeat) > + seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); Shouldn't that be "%.*s" ? Also, isn't this likely to end up walking past the end of "pfx" (or even ending up at an address before the buffer)? You have this below: lock_get_status(f, fl, *id, "", 0); ...so the "length" value you're passing into the format there is going to be -1. It also seems like if you get a large "level" value in locks_show, then you'll end up with a length that is much longer than the actual string. > + > if (IS_POSIX(fl)) { > if (fl->fl_flags & FL_ACCESS) > seq_puts(f, "ACCESS"); > @@ -2906,21 +2910,64 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, > } > } > > > > > +static struct file_lock *get_next_blocked_member(struct file_lock *node) > +{ > + struct file_lock *tmp; > + > + /* NULL node or root node */ > + if (node == NULL || node->fl_blocker == NULL) > + return NULL; > + > + /* Next member in the linked list could be itself */ > + tmp = list_next_entry(node, fl_blocked_member); > + if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member) > + || tmp == node) { > + return NULL; > + } > + > + return tmp; > +} > + > static int locks_show(struct seq_file *f, void *v) > { > struct locks_iterator *iter = f->private; > - struct file_lock *fl, *bfl; > + struct file_lock *cur, *tmp; > struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); > + int level = 0; > > > > > - fl = hlist_entry(v, struct file_lock, fl_link); > + cur = hlist_entry(v, struct file_lock, fl_link); > > > > > - if (locks_translate_pid(fl, proc_pidns) == 0) > + if (locks_translate_pid(cur, proc_pidns) == 0) > return 0; > > > > > - lock_get_status(f, fl, iter->li_pos, ""); > + /* View this crossed linked list as a binary tree, the first member of fl_blocked_requests > + * is the left child of current node, the next silibing in fl_blocked_member is the > + * right child, we can alse get the parent of current node from fl_blocker, so this > + * question becomes traversal of a binary tree > + */ > + while (cur != NULL) { > + if (level) > + lock_get_status(f, cur, iter->li_pos, "-> ", level); > + else > + lock_get_status(f, cur, iter->li_pos, "", level); > > > > > - list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member) > - lock_get_status(f, bfl, iter->li_pos, " ->"); > + if (!list_empty(&cur->fl_blocked_requests)) { > + /* Turn left */ > + cur = list_first_entry_or_null(&cur->fl_blocked_requests, > + struct file_lock, fl_blocked_member); > + level++; > + } else { > + /* Turn right */ > + tmp = get_next_blocked_member(cur); > + /* Fall back to parent node */ > + while (tmp == NULL && cur->fl_blocker != NULL) { > + cur = cur->fl_blocker; > + level--; > + tmp = get_next_blocked_member(cur); > + } > + cur = tmp; > + } > + } > > > > > return 0; > } > @@ -2941,7 +2988,7 @@ static void __show_fd_locks(struct seq_file *f, > > > > > (*id)++; > seq_puts(f, "lock:\t"); > - lock_get_status(f, fl, *id, ""); > + lock_get_status(f, fl, *id, "", 0); > } > } > > > >
在 2021/3/9 21:37, Jeff Layton 写道: > On Thu, 2021-02-25 at 22:58 -0500, Luo Longjun wrote: >> Commit fd7732e033e3 ("fs/locks: create a tree of dependent requests.") >> has put blocked locks into a tree. >> >> So, with a for loop, we can't check all locks information. >> >> To solve this problem, we should traverse the tree. >> >> Signed-off-by: Luo Longjun <luolongjun@huawei.com> >> --- >> fs/locks.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++-------- >> 1 file changed, 56 insertions(+), 9 deletions(-) >> >> diff --git a/fs/locks.c b/fs/locks.c >> index 99ca97e81b7a..ecaecd1f1b58 100644 >> --- a/fs/locks.c >> +++ b/fs/locks.c >> @@ -2828,7 +2828,7 @@ struct locks_iterator { >> }; >> >> >> >> >> static void lock_get_status(struct seq_file *f, struct file_lock *fl, >> - loff_t id, char *pfx) >> + loff_t id, char *pfx, int repeat) >> { >> struct inode *inode = NULL; >> unsigned int fl_pid; >> @@ -2844,7 +2844,11 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, >> if (fl->fl_file != NULL) >> inode = locks_inode(fl->fl_file); >> >> >> >> >> - seq_printf(f, "%lld:%s ", id, pfx); >> + seq_printf(f, "%lld: ", id); >> + >> + if (repeat) >> + seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); > Shouldn't that be "%.*s" ? > > Also, isn't this likely to end up walking past the end of "pfx" (or even > ending up at an address before the buffer)? You have this below: > > lock_get_status(f, fl, *id, "", 0); > > ...so the "length" value you're passing into the format there is going > to be -1. It also seems like if you get a large "level" value in > locks_show, then you'll end up with a length that is much longer than > the actual string. In my understanding, the difference of "%*s" and "%.*s" is that, "%*s" specifies the minimal filed width while "%.*s" specifies the precision of the string. Here, I use "%*s", because I want to print locks information in the follwing format: 2: FLOCK ADVISORY WRITE 110 00:02:493 0 EOF 2: -> FLOCK ADVISORY WRITE 111 00:02:493 0 EOF 2: -> FLOCK ADVISORY WRITE 112 00:02:493 0 EOF 2: -> FLOCK ADVISORY WRITE 113 00:02:493 0 EOF 2: -> FLOCK ADVISORY WRITE 114 00:02:493 0 EOF And also, there is another way to show there information, in the format like: 60: FLOCK ADVISORY WRITE 23350 08:02:4456514 0 EOF 60: -> FLOCK ADVISORY WRITE 23356 08:02:4456514 0 EOF 60: -> FLOCK ADVISORY WRITE 24217 08:02:4456514 0 EOF 60: -> FLOCK ADVISORY WRITE 24239 08:02:4456514 0 EOF I think both formats are acceptable, but the first format shows competition relationships between these locks. In the following code: > lock_get_status(f, fl, *id, "", 0); repeat is 0, and in the function: + if (repeat) + seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); The if branch will not take effect, so it could not be -1. >> + >> if (IS_POSIX(fl)) { >> if (fl->fl_flags & FL_ACCESS) >> seq_puts(f, "ACCESS"); >> @@ -2906,21 +2910,64 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, >> } >> } >> >> >> >> >> +static struct file_lock *get_next_blocked_member(struct file_lock *node) >> +{ >> + struct file_lock *tmp; >> + >> + /* NULL node or root node */ >> + if (node == NULL || node->fl_blocker == NULL) >> + return NULL; >> + >> + /* Next member in the linked list could be itself */ >> + tmp = list_next_entry(node, fl_blocked_member); >> + if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member) >> + || tmp == node) { >> + return NULL; >> + } >> + >> + return tmp; >> +} >> + >> static int locks_show(struct seq_file *f, void *v) >> { >> struct locks_iterator *iter = f->private; >> - struct file_lock *fl, *bfl; >> + struct file_lock *cur, *tmp; >> struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); >> + int level = 0; >> >> >> >> >> - fl = hlist_entry(v, struct file_lock, fl_link); >> + cur = hlist_entry(v, struct file_lock, fl_link); >> >> >> >> >> - if (locks_translate_pid(fl, proc_pidns) == 0) >> + if (locks_translate_pid(cur, proc_pidns) == 0) >> return 0; >> >> >> >> >> - lock_get_status(f, fl, iter->li_pos, ""); >> + /* View this crossed linked list as a binary tree, the first member of fl_blocked_requests >> + * is the left child of current node, the next silibing in fl_blocked_member is the >> + * right child, we can alse get the parent of current node from fl_blocker, so this >> + * question becomes traversal of a binary tree >> + */ >> + while (cur != NULL) { >> + if (level) >> + lock_get_status(f, cur, iter->li_pos, "-> ", level); >> + else >> + lock_get_status(f, cur, iter->li_pos, "", level); >> >> >> >> >> - list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member) >> - lock_get_status(f, bfl, iter->li_pos, " ->"); >> + if (!list_empty(&cur->fl_blocked_requests)) { >> + /* Turn left */ >> + cur = list_first_entry_or_null(&cur->fl_blocked_requests, >> + struct file_lock, fl_blocked_member); >> + level++; >> + } else { >> + /* Turn right */ >> + tmp = get_next_blocked_member(cur); >> + /* Fall back to parent node */ >> + while (tmp == NULL && cur->fl_blocker != NULL) { >> + cur = cur->fl_blocker; >> + level--; >> + tmp = get_next_blocked_member(cur); >> + } >> + cur = tmp; >> + } >> + } >> >> >> >> >> return 0; >> } >> @@ -2941,7 +2988,7 @@ static void __show_fd_locks(struct seq_file *f, >> >> >> >> >> (*id)++; >> seq_puts(f, "lock:\t"); >> - lock_get_status(f, fl, *id, ""); >> + lock_get_status(f, fl, *id, "", 0); >> } >> } >> >> >> >>
On Thu, 2021-03-11 at 11:45 +0800, Luo Longjun wrote: > 在 2021/3/9 21:37, Jeff Layton 写道: > > On Thu, 2021-02-25 at 22:58 -0500, Luo Longjun wrote: > > > Commit fd7732e033e3 ("fs/locks: create a tree of dependent requests.") > > > has put blocked locks into a tree. > > > > > > So, with a for loop, we can't check all locks information. > > > > > > To solve this problem, we should traverse the tree. > > > > > > Signed-off-by: Luo Longjun <luolongjun@huawei.com> > > > --- > > > fs/locks.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++-------- > > > 1 file changed, 56 insertions(+), 9 deletions(-) > > > > > > diff --git a/fs/locks.c b/fs/locks.c > > > index 99ca97e81b7a..ecaecd1f1b58 100644 > > > --- a/fs/locks.c > > > +++ b/fs/locks.c > > > @@ -2828,7 +2828,7 @@ struct locks_iterator { > > > }; > > > > > > > > > > > > > > > > > > > > > > > > static void lock_get_status(struct seq_file *f, struct file_lock *fl, > > > - loff_t id, char *pfx) > > > + loff_t id, char *pfx, int repeat) > > > { > > > struct inode *inode = NULL; > > > unsigned int fl_pid; > > > @@ -2844,7 +2844,11 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, > > > if (fl->fl_file != NULL) > > > inode = locks_inode(fl->fl_file); > > > > > > > > > > > > > > > > > > > > > > > > - seq_printf(f, "%lld:%s ", id, pfx); > > > + seq_printf(f, "%lld: ", id); > > > + > > > + if (repeat) > > > + seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); > > Shouldn't that be "%.*s" ? > > > > Also, isn't this likely to end up walking past the end of "pfx" (or even > > ending up at an address before the buffer)? You have this below: > > > > lock_get_status(f, fl, *id, "", 0); > > > > ...so the "length" value you're passing into the format there is going > > to be -1. It also seems like if you get a large "level" value in > > locks_show, then you'll end up with a length that is much longer than > > the actual string. > > In my understanding, the difference of "%*s" and "%.*s" is that, "%*s" > specifies the minimal filed width while "%.*s" specifies the precision > of the string. > Oh, right. I always forget about the first usage. > Here, I use "%*s", because I want to print locks information in the > follwing format: > > 2: FLOCK ADVISORY WRITE 110 00:02:493 0 EOF > 2: -> FLOCK ADVISORY WRITE 111 00:02:493 0 EOF > 2: -> FLOCK ADVISORY WRITE 112 00:02:493 0 EOF > 2: -> FLOCK ADVISORY WRITE 113 00:02:493 0 EOF > 2: -> FLOCK ADVISORY WRITE 114 00:02:493 0 EOF > > And also, there is another way to show there information, in the format > like: > > 60: FLOCK ADVISORY WRITE 23350 08:02:4456514 0 EOF > 60: -> FLOCK ADVISORY WRITE 23356 08:02:4456514 0 EOF > 60: -> FLOCK ADVISORY WRITE 24217 08:02:4456514 0 EOF > 60: -> FLOCK ADVISORY WRITE 24239 08:02:4456514 0 EOF > > I think both formats are acceptable, but the first format shows > competition relationships between these locks. > We might as well go with the one this patch implements. I like seeing the chain of waiters as well, and it doesn't seem to break lslocks (which is, to my knowledge, the only real programmatic consumer of this file). > In the following code: > > > lock_get_status(f, fl, *id, "", 0); > > repeat is 0, and in the function: > > + if (repeat) > + seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); > > The if branch will not take effect, so it could not be -1. > Good point. Ok, I'll go ahead and put this one in linux-next for now. Assuming there are no problems, it should make v5.13. Thanks!
diff --git a/fs/locks.c b/fs/locks.c index 99ca97e81b7a..ecaecd1f1b58 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -2828,7 +2828,7 @@ struct locks_iterator { }; static void lock_get_status(struct seq_file *f, struct file_lock *fl, - loff_t id, char *pfx) + loff_t id, char *pfx, int repeat) { struct inode *inode = NULL; unsigned int fl_pid; @@ -2844,7 +2844,11 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, if (fl->fl_file != NULL) inode = locks_inode(fl->fl_file); - seq_printf(f, "%lld:%s ", id, pfx); + seq_printf(f, "%lld: ", id); + + if (repeat) + seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); + if (IS_POSIX(fl)) { if (fl->fl_flags & FL_ACCESS) seq_puts(f, "ACCESS"); @@ -2906,21 +2910,64 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, } } +static struct file_lock *get_next_blocked_member(struct file_lock *node) +{ + struct file_lock *tmp; + + /* NULL node or root node */ + if (node == NULL || node->fl_blocker == NULL) + return NULL; + + /* Next member in the linked list could be itself */ + tmp = list_next_entry(node, fl_blocked_member); + if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member) + || tmp == node) { + return NULL; + } + + return tmp; +} + static int locks_show(struct seq_file *f, void *v) { struct locks_iterator *iter = f->private; - struct file_lock *fl, *bfl; + struct file_lock *cur, *tmp; struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); + int level = 0; - fl = hlist_entry(v, struct file_lock, fl_link); + cur = hlist_entry(v, struct file_lock, fl_link); - if (locks_translate_pid(fl, proc_pidns) == 0) + if (locks_translate_pid(cur, proc_pidns) == 0) return 0; - lock_get_status(f, fl, iter->li_pos, ""); + /* View this crossed linked list as a binary tree, the first member of fl_blocked_requests + * is the left child of current node, the next silibing in fl_blocked_member is the + * right child, we can alse get the parent of current node from fl_blocker, so this + * question becomes traversal of a binary tree + */ + while (cur != NULL) { + if (level) + lock_get_status(f, cur, iter->li_pos, "-> ", level); + else + lock_get_status(f, cur, iter->li_pos, "", level); - list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member) - lock_get_status(f, bfl, iter->li_pos, " ->"); + if (!list_empty(&cur->fl_blocked_requests)) { + /* Turn left */ + cur = list_first_entry_or_null(&cur->fl_blocked_requests, + struct file_lock, fl_blocked_member); + level++; + } else { + /* Turn right */ + tmp = get_next_blocked_member(cur); + /* Fall back to parent node */ + while (tmp == NULL && cur->fl_blocker != NULL) { + cur = cur->fl_blocker; + level--; + tmp = get_next_blocked_member(cur); + } + cur = tmp; + } + } return 0; } @@ -2941,7 +2988,7 @@ static void __show_fd_locks(struct seq_file *f, (*id)++; seq_puts(f, "lock:\t"); - lock_get_status(f, fl, *id, ""); + lock_get_status(f, fl, *id, "", 0); } }
Commit fd7732e033e3 ("fs/locks: create a tree of dependent requests.") has put blocked locks into a tree. So, with a for loop, we can't check all locks information. To solve this problem, we should traverse the tree. Signed-off-by: Luo Longjun <luolongjun@huawei.com> --- fs/locks.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 56 insertions(+), 9 deletions(-)