| Message ID | 1683026600-13485-3-git-send-email-akaher@vmware.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tracing: introducing eventfs | expand |
On 2023/5/2 19:23, Ajay Kaher wrote: > Adding eventfs_file structure which will hold properties of file or dir. > > Adding following functions to add dir in eventfs: > > eventfs_create_events_dir() will directly create events dir with-in > tracing folder. > > eventfs_add_subsystem_dir() will adds the info of subsystem_dir to > eventfs and dynamically create subsystem_dir as and when requires. > > eventfs_add_dir() will add the info of dir (which is with-in > subsystem_dir) to eventfs and dynamically create these dir as > and when requires. > > Signed-off-by: Ajay Kaher <akaher@vmware.com> > Co-developed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > Tested-by: Ching-lin Yu <chinglinyu@google.com> > --- > fs/tracefs/Makefile | 1 + > fs/tracefs/event_inode.c | 252 +++++++++++++++++++++++++++++++++++++++ > include/linux/tracefs.h | 29 +++++ > kernel/trace/trace.h | 1 + > 4 files changed, 283 insertions(+) > create mode 100644 fs/tracefs/event_inode.c > > diff --git a/fs/tracefs/Makefile b/fs/tracefs/Makefile > index 7c35a282b..73c56da8e 100644 > --- a/fs/tracefs/Makefile > +++ b/fs/tracefs/Makefile > @@ -1,5 +1,6 @@ > # SPDX-License-Identifier: GPL-2.0-only > tracefs-objs := inode.o > +tracefs-objs += event_inode.o > > obj-$(CONFIG_TRACING) += tracefs.o > > diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c > new file mode 100644 > index 000000000..82caba7e9 > --- /dev/null > +++ b/fs/tracefs/event_inode.c > @@ -0,0 +1,252 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * event_inode.c - part of tracefs, a pseudo file system for activating tracing > + * > + * Copyright (C) 2020-22 VMware Inc, author: Steven Rostedt (VMware) <rostedt@goodmis.org> > + * Copyright (C) 2020-22 VMware Inc, author: Ajay Kaher <akaher@vmware.com> > + * > + * eventfs is used to show trace events with one set of dentries > + * > + * eventfs stores meta-data of files/dirs and skip to create object of > + * inodes/dentries. As and when requires, eventfs will create the > + * inodes/dentries for only required files/directories. Also eventfs > + * would delete the inodes/dentries once no more requires but preserve > + * the meta data. > + */ > +#include <linux/fsnotify.h> > +#include <linux/fs.h> > +#include <linux/namei.h> > +#include <linux/security.h> > +#include <linux/tracefs.h> > +#include <linux/kref.h> > +#include <linux/delay.h> > +#include "internal.h" > + > +/** > + * eventfs_dentry_to_rwsem - Return corresponding eventfs_rwsem > + * @dentry: a pointer to dentry > + * > + * helper function to return crossponding eventfs_rwsem for given dentry > + */ > +static struct rw_semaphore *eventfs_dentry_to_rwsem(struct dentry *dentry) > +{ > + if (S_ISDIR(dentry->d_inode->i_mode)) > + return (struct rw_semaphore *)dentry->d_inode->i_private; > + else > + return (struct rw_semaphore *)dentry->d_parent->d_inode->i_private; > +} > + > +/** > + * eventfs_down_read - acquire read lock function > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * helper function to perform read lock, skip locking if caller task already > + * own the lock. read lock requires for lookup(), release() and these also > + * called with-in open(), remove() which already hold the read/write lock. > + */ > +static void eventfs_down_read(struct rw_semaphore *eventfs_rwsem) > +{ > + down_read_nested(eventfs_rwsem, SINGLE_DEPTH_NESTING); > +} > + > +/** > + * eventfs_up_read - release read lock function > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * helper function to release eventfs_rwsem lock if locked > + */ > +static void eventfs_up_read(struct rw_semaphore *eventfs_rwsem) > +{ > + up_read(eventfs_rwsem); > +} > + > +/** > + * eventfs_down_write - acquire write lock function > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * helper function to perform write lock on eventfs_rwsem > + */ > +static void eventfs_down_write(struct rw_semaphore *eventfs_rwsem) > +{ > + while (!down_write_trylock(eventfs_rwsem)) > + msleep(10); > +} > + > +/** > + * eventfs_up_write - release write lock function > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * helper function to perform write lock on eventfs_rwsem > + */ > +static void eventfs_up_write(struct rw_semaphore *eventfs_rwsem) > +{ > + up_write(eventfs_rwsem); > +} > + > +static const struct file_operations eventfs_file_operations = { > +}; > + > +static const struct inode_operations eventfs_root_dir_inode_operations = { > +}; > + > +/** > + * eventfs_create_events_dir - create the trace event structure > + * @name: a pointer to a string containing the name of the directory to > + * create. > + * @parent: a pointer to the parent dentry for this file. This should be a > + * directory dentry if set. If this parameter is NULL, then the > + * directory will be created in the root of the tracefs filesystem. > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * This function creates the top of the trace event directory. > + */ > +struct dentry *eventfs_create_events_dir(const char *name, > + struct dentry *parent, > + struct rw_semaphore *eventfs_rwsem) > +{ > + struct dentry *dentry = tracefs_start_creating(name, parent); > + struct eventfs_inode *ei; > + struct tracefs_inode *ti; > + struct inode *inode; > + > + if (IS_ERR(dentry)) > + return dentry; > + > + ei = kzalloc(sizeof(*ei), GFP_KERNEL); > + if (!ei) > + return ERR_PTR(-ENOMEM); > + inode = tracefs_get_inode(dentry->d_sb); > + if (unlikely(!inode)) { > + kfree(ei); > + tracefs_failed_creating(dentry); > + return ERR_PTR(-ENOMEM); > + } > + > + init_rwsem(eventfs_rwsem); > + INIT_LIST_HEAD(&ei->e_top_files); > + > + ti = get_tracefs(inode); > + ti->flags |= TRACEFS_EVENT_INODE; > + ti->private = ei; > + > + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; > + inode->i_op = &eventfs_root_dir_inode_operations; > + inode->i_fop = &eventfs_file_operations; > + inode->i_private = eventfs_rwsem; > + > + /* directory inodes start off with i_nlink == 2 (for "." entry) */ > + inc_nlink(inode); > + d_instantiate(dentry, inode); > + inc_nlink(dentry->d_parent->d_inode); > + fsnotify_mkdir(dentry->d_parent->d_inode, dentry); > + return tracefs_end_creating(dentry); > +} > + > +/** > + * eventfs_add_subsystem_dir - add eventfs subsystem_dir to list to create later > + * @name: a pointer to a string containing the name of the file to create. > + * @parent: a pointer to the parent dentry for this dir. > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * This function adds eventfs subsystem dir to list. > + * And all these dirs are created on the fly when they are looked up, > + * and the dentry and inodes will be removed when they are done. > + */ > +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, > + struct dentry *parent, > + struct rw_semaphore *eventfs_rwsem) > +{ > + struct tracefs_inode *ti_parent; > + struct eventfs_inode *ei_parent; > + struct eventfs_file *ef; > + > + if (!parent) > + return ERR_PTR(-EINVAL); > + > + ti_parent = get_tracefs(parent->d_inode); > + ei_parent = ti_parent->private; > + > + ef = kzalloc(sizeof(*ef), GFP_KERNEL); > + if (!ef) > + return ERR_PTR(-ENOMEM); > + > + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); > + if (!ef->ei) { > + kfree(ef); > + return ERR_PTR(-ENOMEM); > + } > + > + INIT_LIST_HEAD(&ef->ei->e_top_files); > + > + ef->name = kstrdup(name, GFP_KERNEL); > + if (!ef->name) { > + kfree(ef->ei); > + kfree(ef); > + return ERR_PTR(-ENOMEM); > + } > + > + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; > + ef->iop = &eventfs_root_dir_inode_operations; > + ef->fop = &eventfs_file_operations; > + ef->dentry = NULL; > + ef->created = false; > + ef->d_parent = parent; > + ef->data = eventfs_rwsem; > + > + eventfs_down_write(eventfs_rwsem); > + list_add_tail(&ef->list, &ei_parent->e_top_files); > + eventfs_up_write(eventfs_rwsem); > + return ef; > +} > + > +/** > + * eventfs_add_dir - add eventfs dir to list to create later > + * @name: a pointer to a string containing the name of the file to create. > + * @ef_parent: a pointer to the parent eventfs_file for this dir. > + * @eventfs_rwsem: a pointer to rw_semaphore > + * > + * This function adds eventfs dir to list. > + * And all these dirs are created on the fly when they are looked up, > + * and the dentry and inodes will be removed when they are done. > + */ > +struct eventfs_file *eventfs_add_dir(const char *name, > + struct eventfs_file *ef_parent, > + struct rw_semaphore *eventfs_rwsem) > +{ > + struct eventfs_file *ef; > + > + if (!ef_parent) > + return ERR_PTR(-EINVAL); > + > + ef = kzalloc(sizeof(*ef), GFP_KERNEL); > + if (!ef) > + return ERR_PTR(-ENOMEM); > + > + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); > + if (!ef->ei) { > + kfree(ef); > + return ERR_PTR(-ENOMEM); > + } > + > + INIT_LIST_HEAD(&ef->ei->e_top_files); > + > + ef->name = kstrdup(name, GFP_KERNEL); > + if (!ef->name) { > + kfree(ef->ei); > + kfree(ef); > + return ERR_PTR(-ENOMEM); > + } > + > + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; > + ef->iop = &eventfs_root_dir_inode_operations; > + ef->fop = &eventfs_file_operations; > + ef->created = false; > + ef->dentry = NULL; > + ef->d_parent = NULL; > + ef->data = eventfs_rwsem; > + > + eventfs_down_write(eventfs_rwsem); > + list_add_tail(&ef->list, &ef_parent->ei->e_top_files); > + eventfs_up_write(eventfs_rwsem); > + return ef; > +} Hi, eventfs_add_subsystem_dir() and eventfs_add_dir() are almost the same, how about extract a common help function to simplify them, like: +static struct eventfs_file *__eventfs_add_dir(const char *name, + struct dentry *d_parent, + struct eventfs_inode *ei_parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct eventfs_file *ef; + + ef = kzalloc(sizeof(*ef), GFP_KERNEL); + if (!ef) + return ERR_PTR(-ENOMEM); + + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); + if (!ef->ei) { + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + INIT_LIST_HEAD(&ef->ei->e_top_files); + + ef->name = kstrdup(name, GFP_KERNEL); + if (!ef->name) { + kfree(ef->ei); + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + ef->iop = &eventfs_root_dir_inode_operations; + ef->fop = &eventfs_file_operations; + ef->dentry = NULL; + ef->created = false; + ef->d_parent = d_parent; + ef->data = eventfs_rwsem; + + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ei_parent->e_top_files); + eventfs_up_write(eventfs_rwsem); + return ef; +} + +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct tracefs_inode *ti_parent; + struct eventfs_inode *ei_parent; + + if (!parent) + return ERR_PTR(-EINVAL); + ti_parent = get_tracefs(parent->d_inode); + ei_parent = ti_parent->private; + return __eventfs_add_dir(name, parent, ei_parent, eventfs_rwsem); +} + +struct eventfs_file *eventfs_add_dir(const char *name, + struct eventfs_file *ef_parent, + struct rw_semaphore *eventfs_rwsem) +{ + if (!ef_parent) + return ERR_PTR(-EINVAL); + return __eventfs_add_dir(name, NULL, ef_parent->ei, eventfs_rwsem); +} -- Best regards, Zheng Yejian > diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h > index 999124459..aeca6761f 100644 > --- a/include/linux/tracefs.h > +++ b/include/linux/tracefs.h > @@ -21,6 +21,35 @@ struct file_operations; > > #ifdef CONFIG_TRACING > > +struct eventfs_inode { > + struct list_head e_top_files; > +}; > + > +struct eventfs_file { > + const char *name; > + struct dentry *d_parent; > + struct dentry *dentry; > + struct list_head list; > + struct eventfs_inode *ei; > + const struct file_operations *fop; > + const struct inode_operations *iop; > + void *data; > + umode_t mode; > + bool created; > +}; > + > +struct dentry *eventfs_create_events_dir(const char *name, > + struct dentry *parent, > + struct rw_semaphore *eventfs_rwsem); > + > +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, > + struct dentry *parent, > + struct rw_semaphore *eventfs_rwsem); > + > +struct eventfs_file *eventfs_add_dir(const char *name, > + struct eventfs_file *ef_parent, > + struct rw_semaphore *eventfs_rwsem); > + > struct dentry *tracefs_create_file(const char *name, umode_t mode, > struct dentry *parent, void *data, > const struct file_operations *fops); > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 616e1aa1c..3726725c8 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -359,6 +359,7 @@ struct trace_array { > struct dentry *options; > struct dentry *percpu_dir; > struct dentry *event_dir; > + struct rw_semaphore eventfs_rwsem; > struct trace_options *topts; > struct list_head systems; > struct list_head events;
> On 08-May-2023, at 3:02 PM, Zheng Yejian <zhengyejian1@huawei.com> wrote: > > On 2023/5/2 19:23, Ajay Kaher wrote: >> Adding eventfs_file structure which will hold properties of file or dir. >> >> Adding following functions to add dir in eventfs: >> >> eventfs_create_events_dir() will directly create events dir with-in >> tracing folder. >> >> eventfs_add_subsystem_dir() will adds the info of subsystem_dir to >> eventfs and dynamically create subsystem_dir as and when requires. >> >> eventfs_add_dir() will add the info of dir (which is with-in >> subsystem_dir) to eventfs and dynamically create these dir as >> and when requires. >> >> Signed-off-by: Ajay Kaher <akaher@vmware.com> >> Co-developed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> >> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> >> Tested-by: Ching-lin Yu <chinglinyu@google.com> >> --- >> fs/tracefs/Makefile | 1 + >> fs/tracefs/event_inode.c | 252 +++++++++++++++++++++++++++++++++++++++ >> include/linux/tracefs.h | 29 +++++ >> kernel/trace/trace.h | 1 + >> 4 files changed, 283 insertions(+) >> create mode 100644 fs/tracefs/event_inode.c >> >> diff --git a/fs/tracefs/Makefile b/fs/tracefs/Makefile >> index 7c35a282b..73c56da8e 100644 >> --- a/fs/tracefs/Makefile >> +++ b/fs/tracefs/Makefile >> @@ -1,5 +1,6 @@ >> # SPDX-License-Identifier: GPL-2.0-only >> tracefs-objs := inode.o >> +tracefs-objs += event_inode.o >> >> obj-$(CONFIG_TRACING) += tracefs.o >> >> diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c >> new file mode 100644 >> index 000000000..82caba7e9 >> --- /dev/null >> +++ b/fs/tracefs/event_inode.c >> @@ -0,0 +1,252 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * event_inode.c - part of tracefs, a pseudo file system for activating tracing >> + * >> + * Copyright (C) 2020-22 VMware Inc, author: Steven Rostedt (VMware) <rostedt@goodmis.org> >> + * Copyright (C) 2020-22 VMware Inc, author: Ajay Kaher <akaher@vmware.com> >> + * >> + * eventfs is used to show trace events with one set of dentries >> + * >> + * eventfs stores meta-data of files/dirs and skip to create object of >> + * inodes/dentries. As and when requires, eventfs will create the >> + * inodes/dentries for only required files/directories. Also eventfs >> + * would delete the inodes/dentries once no more requires but preserve >> + * the meta data. >> + */ >> +#include <linux/fsnotify.h> >> +#include <linux/fs.h> >> +#include <linux/namei.h> >> +#include <linux/security.h> >> +#include <linux/tracefs.h> >> +#include <linux/kref.h> >> +#include <linux/delay.h> >> +#include "internal.h" >> + >> +/** >> + * eventfs_dentry_to_rwsem - Return corresponding eventfs_rwsem >> + * @dentry: a pointer to dentry >> + * >> + * helper function to return crossponding eventfs_rwsem for given dentry >> + */ >> +static struct rw_semaphore *eventfs_dentry_to_rwsem(struct dentry *dentry) >> +{ >> + if (S_ISDIR(dentry->d_inode->i_mode)) >> + return (struct rw_semaphore *)dentry->d_inode->i_private; >> + else >> + return (struct rw_semaphore *)dentry->d_parent->d_inode->i_private; >> +} >> + >> +/** >> + * eventfs_down_read - acquire read lock function >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * helper function to perform read lock, skip locking if caller task already >> + * own the lock. read lock requires for lookup(), release() and these also >> + * called with-in open(), remove() which already hold the read/write lock. >> + */ >> +static void eventfs_down_read(struct rw_semaphore *eventfs_rwsem) >> +{ >> + down_read_nested(eventfs_rwsem, SINGLE_DEPTH_NESTING); >> +} >> + >> +/** >> + * eventfs_up_read - release read lock function >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * helper function to release eventfs_rwsem lock if locked >> + */ >> +static void eventfs_up_read(struct rw_semaphore *eventfs_rwsem) >> +{ >> + up_read(eventfs_rwsem); >> +} >> + >> +/** >> + * eventfs_down_write - acquire write lock function >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * helper function to perform write lock on eventfs_rwsem >> + */ >> +static void eventfs_down_write(struct rw_semaphore *eventfs_rwsem) >> +{ >> + while (!down_write_trylock(eventfs_rwsem)) >> + msleep(10); >> +} >> + >> +/** >> + * eventfs_up_write - release write lock function >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * helper function to perform write lock on eventfs_rwsem >> + */ >> +static void eventfs_up_write(struct rw_semaphore *eventfs_rwsem) >> +{ >> + up_write(eventfs_rwsem); >> +} >> + >> +static const struct file_operations eventfs_file_operations = { >> +}; >> + >> +static const struct inode_operations eventfs_root_dir_inode_operations = { >> +}; >> + >> +/** >> + * eventfs_create_events_dir - create the trace event structure >> + * @name: a pointer to a string containing the name of the directory to >> + * create. >> + * @parent: a pointer to the parent dentry for this file. This should be a >> + * directory dentry if set. If this parameter is NULL, then the >> + * directory will be created in the root of the tracefs filesystem. >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * This function creates the top of the trace event directory. >> + */ >> +struct dentry *eventfs_create_events_dir(const char *name, >> + struct dentry *parent, >> + struct rw_semaphore *eventfs_rwsem) >> +{ >> + struct dentry *dentry = tracefs_start_creating(name, parent); >> + struct eventfs_inode *ei; >> + struct tracefs_inode *ti; >> + struct inode *inode; >> + >> + if (IS_ERR(dentry)) >> + return dentry; >> + >> + ei = kzalloc(sizeof(*ei), GFP_KERNEL); >> + if (!ei) >> + return ERR_PTR(-ENOMEM); >> + inode = tracefs_get_inode(dentry->d_sb); >> + if (unlikely(!inode)) { >> + kfree(ei); >> + tracefs_failed_creating(dentry); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + init_rwsem(eventfs_rwsem); >> + INIT_LIST_HEAD(&ei->e_top_files); >> + >> + ti = get_tracefs(inode); >> + ti->flags |= TRACEFS_EVENT_INODE; >> + ti->private = ei; >> + >> + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; >> + inode->i_op = &eventfs_root_dir_inode_operations; >> + inode->i_fop = &eventfs_file_operations; >> + inode->i_private = eventfs_rwsem; >> + >> + /* directory inodes start off with i_nlink == 2 (for "." entry) */ >> + inc_nlink(inode); >> + d_instantiate(dentry, inode); >> + inc_nlink(dentry->d_parent->d_inode); >> + fsnotify_mkdir(dentry->d_parent->d_inode, dentry); >> + return tracefs_end_creating(dentry); >> +} >> + >> +/** >> + * eventfs_add_subsystem_dir - add eventfs subsystem_dir to list to create later >> + * @name: a pointer to a string containing the name of the file to create. >> + * @parent: a pointer to the parent dentry for this dir. >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * This function adds eventfs subsystem dir to list. >> + * And all these dirs are created on the fly when they are looked up, >> + * and the dentry and inodes will be removed when they are done. >> + */ >> +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, >> + struct dentry *parent, >> + struct rw_semaphore *eventfs_rwsem) >> +{ >> + struct tracefs_inode *ti_parent; >> + struct eventfs_inode *ei_parent; >> + struct eventfs_file *ef; >> + >> + if (!parent) >> + return ERR_PTR(-EINVAL); >> + >> + ti_parent = get_tracefs(parent->d_inode); >> + ei_parent = ti_parent->private; >> + >> + ef = kzalloc(sizeof(*ef), GFP_KERNEL); >> + if (!ef) >> + return ERR_PTR(-ENOMEM); >> + >> + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); >> + if (!ef->ei) { >> + kfree(ef); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + INIT_LIST_HEAD(&ef->ei->e_top_files); >> + >> + ef->name = kstrdup(name, GFP_KERNEL); >> + if (!ef->name) { >> + kfree(ef->ei); >> + kfree(ef); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; >> + ef->iop = &eventfs_root_dir_inode_operations; >> + ef->fop = &eventfs_file_operations; >> + ef->dentry = NULL; >> + ef->created = false; >> + ef->d_parent = parent; >> + ef->data = eventfs_rwsem; >> + >> + eventfs_down_write(eventfs_rwsem); >> + list_add_tail(&ef->list, &ei_parent->e_top_files); >> + eventfs_up_write(eventfs_rwsem); >> + return ef; >> +} >> + >> +/** >> + * eventfs_add_dir - add eventfs dir to list to create later >> + * @name: a pointer to a string containing the name of the file to create. >> + * @ef_parent: a pointer to the parent eventfs_file for this dir. >> + * @eventfs_rwsem: a pointer to rw_semaphore >> + * >> + * This function adds eventfs dir to list. >> + * And all these dirs are created on the fly when they are looked up, >> + * and the dentry and inodes will be removed when they are done. >> + */ >> +struct eventfs_file *eventfs_add_dir(const char *name, >> + struct eventfs_file *ef_parent, >> + struct rw_semaphore *eventfs_rwsem) >> +{ >> + struct eventfs_file *ef; >> + >> + if (!ef_parent) >> + return ERR_PTR(-EINVAL); >> + >> + ef = kzalloc(sizeof(*ef), GFP_KERNEL); >> + if (!ef) >> + return ERR_PTR(-ENOMEM); >> + >> + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); >> + if (!ef->ei) { >> + kfree(ef); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + INIT_LIST_HEAD(&ef->ei->e_top_files); >> + >> + ef->name = kstrdup(name, GFP_KERNEL); >> + if (!ef->name) { >> + kfree(ef->ei); >> + kfree(ef); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; >> + ef->iop = &eventfs_root_dir_inode_operations; >> + ef->fop = &eventfs_file_operations; >> + ef->created = false; >> + ef->dentry = NULL; >> + ef->d_parent = NULL; >> + ef->data = eventfs_rwsem; >> + >> + eventfs_down_write(eventfs_rwsem); >> + list_add_tail(&ef->list, &ef_parent->ei->e_top_files); >> + eventfs_up_write(eventfs_rwsem); >> + return ef; >> +} > > Hi, > eventfs_add_subsystem_dir() and eventfs_add_dir() are almost the same, > how about extract a common help function to simplify them, like: > > +static struct eventfs_file *__eventfs_add_dir(const char *name, > + struct dentry *d_parent, > + struct eventfs_inode > *ei_parent, > + struct rw_semaphore > *eventfs_rwsem) > +{ > + struct eventfs_file *ef; > + > + ef = kzalloc(sizeof(*ef), GFP_KERNEL); > + if (!ef) > + return ERR_PTR(-ENOMEM); > + > + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); > + if (!ef->ei) { > + kfree(ef); > + return ERR_PTR(-ENOMEM); > + } > + > + INIT_LIST_HEAD(&ef->ei->e_top_files); > + > + ef->name = kstrdup(name, GFP_KERNEL); > + if (!ef->name) { > + kfree(ef->ei); > + kfree(ef); > + return ERR_PTR(-ENOMEM); > + } > + > + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; > + ef->iop = &eventfs_root_dir_inode_operations; > + ef->fop = &eventfs_file_operations; > + ef->dentry = NULL; > + ef->created = false; > + ef->d_parent = d_parent; > + ef->data = eventfs_rwsem; > + > + eventfs_down_write(eventfs_rwsem); > + list_add_tail(&ef->list, &ei_parent->e_top_files); > + eventfs_up_write(eventfs_rwsem); > + return ef; > +} > + > +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, > + struct dentry *parent, > + struct rw_semaphore > *eventfs_rwsem) > +{ > + struct tracefs_inode *ti_parent; > + struct eventfs_inode *ei_parent; > + > + if (!parent) > + return ERR_PTR(-EINVAL); > + ti_parent = get_tracefs(parent->d_inode); > + ei_parent = ti_parent->private; > + return __eventfs_add_dir(name, parent, ei_parent, eventfs_rwsem); > +} > + > +struct eventfs_file *eventfs_add_dir(const char *name, > + struct eventfs_file *ef_parent, > + struct rw_semaphore *eventfs_rwsem) > +{ > + if (!ef_parent) > + return ERR_PTR(-EINVAL); > + return __eventfs_add_dir(name, NULL, ef_parent->ei, eventfs_rwsem); > +} Sounds good. Thanks for sharing code snippet. I will consider in v3. - Ajay >> diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h >> index 999124459..aeca6761f 100644 >> --- a/include/linux/tracefs.h >> +++ b/include/linux/tracefs.h >> @@ -21,6 +21,35 @@ struct file_operations; >> >> #ifdef CONFIG_TRACING >> >> +struct eventfs_inode { >> + struct list_head e_top_files; >> +}; >> + >> +struct eventfs_file { >> + const char *name; >> + struct dentry *d_parent; >> + struct dentry *dentry; >> + struct list_head list; >> + struct eventfs_inode *ei; >> + const struct file_operations *fop; >> + const struct inode_operations *iop; >> + void *data; >> + umode_t mode; >> + bool created; >> +}; >> + >> +struct dentry *eventfs_create_events_dir(const char *name, >> + struct dentry *parent, >> + struct rw_semaphore *eventfs_rwsem); >> + >> +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, >> + struct dentry *parent, >> + struct rw_semaphore *eventfs_rwsem); >> + >> +struct eventfs_file *eventfs_add_dir(const char *name, >> + struct eventfs_file *ef_parent, >> + struct rw_semaphore *eventfs_rwsem); >> + >> struct dentry *tracefs_create_file(const char *name, umode_t mode, >> struct dentry *parent, void *data, >> const struct file_operations *fops); >> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h >> index 616e1aa1c..3726725c8 100644 >> --- a/kernel/trace/trace.h >> +++ b/kernel/trace/trace.h >> @@ -359,6 +359,7 @@ struct trace_array { >> struct dentry *options; >> struct dentry *percpu_dir; >> struct dentry *event_dir; >> + struct rw_semaphore eventfs_rwsem; >> struct trace_options *topts; >> struct list_head systems; >> struct list_head events;
> On 10-May-2023, at 4:55 PM, Ajay Kaher <akaher@vmware.com> wrote: >> >> Hi, >> eventfs_add_subsystem_dir() and eventfs_add_dir() are almost the same, >> how about extract a common help function to simplify them, like: >> >> +static struct eventfs_file *__eventfs_add_dir(const char *name, >> + struct dentry *d_parent, >> + struct eventfs_inode >> *ei_parent, >> + struct rw_semaphore >> *eventfs_rwsem) >> +{ >> + struct eventfs_file *ef; >> + >> + ef = kzalloc(sizeof(*ef), GFP_KERNEL); >> + if (!ef) >> + return ERR_PTR(-ENOMEM); >> + >> + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); >> + if (!ef->ei) { >> + kfree(ef); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + INIT_LIST_HEAD(&ef->ei->e_top_files); >> + >> + ef->name = kstrdup(name, GFP_KERNEL); >> + if (!ef->name) { >> + kfree(ef->ei); >> + kfree(ef); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; >> + ef->iop = &eventfs_root_dir_inode_operations; >> + ef->fop = &eventfs_file_operations; >> + ef->dentry = NULL; >> + ef->created = false; >> + ef->d_parent = d_parent; >> + ef->data = eventfs_rwsem; >> + >> + eventfs_down_write(eventfs_rwsem); >> + list_add_tail(&ef->list, &ei_parent->e_top_files); >> + eventfs_up_write(eventfs_rwsem); >> + return ef; >> +} >> + >> +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, >> + struct dentry *parent, >> + struct rw_semaphore >> *eventfs_rwsem) >> +{ >> + struct tracefs_inode *ti_parent; >> + struct eventfs_inode *ei_parent; >> + >> + if (!parent) >> + return ERR_PTR(-EINVAL); >> + ti_parent = get_tracefs(parent->d_inode); >> + ei_parent = ti_parent->private; >> + return __eventfs_add_dir(name, parent, ei_parent, eventfs_rwsem); >> +} >> + >> +struct eventfs_file *eventfs_add_dir(const char *name, >> + struct eventfs_file *ef_parent, >> + struct rw_semaphore *eventfs_rwsem) >> +{ >> + if (!ef_parent) >> + return ERR_PTR(-EINVAL); >> + return __eventfs_add_dir(name, NULL, ef_parent->ei, eventfs_rwsem); >> +} > > Sounds good. Thanks for sharing code snippet. I will consider in v3. > Hi Zheng, I have moved common code to eventfs_prepare_ef() in v3 3/10, 4/10: https://lore.kernel.org/all/1685610013-33478-1-git-send-email-akaher@vmware.com/ -Ajay
diff --git a/fs/tracefs/Makefile b/fs/tracefs/Makefile index 7c35a282b..73c56da8e 100644 --- a/fs/tracefs/Makefile +++ b/fs/tracefs/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only tracefs-objs := inode.o +tracefs-objs += event_inode.o obj-$(CONFIG_TRACING) += tracefs.o diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c new file mode 100644 index 000000000..82caba7e9 --- /dev/null +++ b/fs/tracefs/event_inode.c @@ -0,0 +1,252 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * event_inode.c - part of tracefs, a pseudo file system for activating tracing + * + * Copyright (C) 2020-22 VMware Inc, author: Steven Rostedt (VMware) <rostedt@goodmis.org> + * Copyright (C) 2020-22 VMware Inc, author: Ajay Kaher <akaher@vmware.com> + * + * eventfs is used to show trace events with one set of dentries + * + * eventfs stores meta-data of files/dirs and skip to create object of + * inodes/dentries. As and when requires, eventfs will create the + * inodes/dentries for only required files/directories. Also eventfs + * would delete the inodes/dentries once no more requires but preserve + * the meta data. + */ +#include <linux/fsnotify.h> +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/security.h> +#include <linux/tracefs.h> +#include <linux/kref.h> +#include <linux/delay.h> +#include "internal.h" + +/** + * eventfs_dentry_to_rwsem - Return corresponding eventfs_rwsem + * @dentry: a pointer to dentry + * + * helper function to return crossponding eventfs_rwsem for given dentry + */ +static struct rw_semaphore *eventfs_dentry_to_rwsem(struct dentry *dentry) +{ + if (S_ISDIR(dentry->d_inode->i_mode)) + return (struct rw_semaphore *)dentry->d_inode->i_private; + else + return (struct rw_semaphore *)dentry->d_parent->d_inode->i_private; +} + +/** + * eventfs_down_read - acquire read lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to perform read lock, skip locking if caller task already + * own the lock. read lock requires for lookup(), release() and these also + * called with-in open(), remove() which already hold the read/write lock. + */ +static void eventfs_down_read(struct rw_semaphore *eventfs_rwsem) +{ + down_read_nested(eventfs_rwsem, SINGLE_DEPTH_NESTING); +} + +/** + * eventfs_up_read - release read lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to release eventfs_rwsem lock if locked + */ +static void eventfs_up_read(struct rw_semaphore *eventfs_rwsem) +{ + up_read(eventfs_rwsem); +} + +/** + * eventfs_down_write - acquire write lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to perform write lock on eventfs_rwsem + */ +static void eventfs_down_write(struct rw_semaphore *eventfs_rwsem) +{ + while (!down_write_trylock(eventfs_rwsem)) + msleep(10); +} + +/** + * eventfs_up_write - release write lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to perform write lock on eventfs_rwsem + */ +static void eventfs_up_write(struct rw_semaphore *eventfs_rwsem) +{ + up_write(eventfs_rwsem); +} + +static const struct file_operations eventfs_file_operations = { +}; + +static const struct inode_operations eventfs_root_dir_inode_operations = { +}; + +/** + * eventfs_create_events_dir - create the trace event structure + * @name: a pointer to a string containing the name of the directory to + * create. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * directory will be created in the root of the tracefs filesystem. + * @eventfs_rwsem: a pointer to rw_semaphore + * + * This function creates the top of the trace event directory. + */ +struct dentry *eventfs_create_events_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct dentry *dentry = tracefs_start_creating(name, parent); + struct eventfs_inode *ei; + struct tracefs_inode *ti; + struct inode *inode; + + if (IS_ERR(dentry)) + return dentry; + + ei = kzalloc(sizeof(*ei), GFP_KERNEL); + if (!ei) + return ERR_PTR(-ENOMEM); + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) { + kfree(ei); + tracefs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); + } + + init_rwsem(eventfs_rwsem); + INIT_LIST_HEAD(&ei->e_top_files); + + ti = get_tracefs(inode); + ti->flags |= TRACEFS_EVENT_INODE; + ti->private = ei; + + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + inode->i_op = &eventfs_root_dir_inode_operations; + inode->i_fop = &eventfs_file_operations; + inode->i_private = eventfs_rwsem; + + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + d_instantiate(dentry, inode); + inc_nlink(dentry->d_parent->d_inode); + fsnotify_mkdir(dentry->d_parent->d_inode, dentry); + return tracefs_end_creating(dentry); +} + +/** + * eventfs_add_subsystem_dir - add eventfs subsystem_dir to list to create later + * @name: a pointer to a string containing the name of the file to create. + * @parent: a pointer to the parent dentry for this dir. + * @eventfs_rwsem: a pointer to rw_semaphore + * + * This function adds eventfs subsystem dir to list. + * And all these dirs are created on the fly when they are looked up, + * and the dentry and inodes will be removed when they are done. + */ +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct tracefs_inode *ti_parent; + struct eventfs_inode *ei_parent; + struct eventfs_file *ef; + + if (!parent) + return ERR_PTR(-EINVAL); + + ti_parent = get_tracefs(parent->d_inode); + ei_parent = ti_parent->private; + + ef = kzalloc(sizeof(*ef), GFP_KERNEL); + if (!ef) + return ERR_PTR(-ENOMEM); + + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); + if (!ef->ei) { + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + INIT_LIST_HEAD(&ef->ei->e_top_files); + + ef->name = kstrdup(name, GFP_KERNEL); + if (!ef->name) { + kfree(ef->ei); + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + ef->iop = &eventfs_root_dir_inode_operations; + ef->fop = &eventfs_file_operations; + ef->dentry = NULL; + ef->created = false; + ef->d_parent = parent; + ef->data = eventfs_rwsem; + + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ei_parent->e_top_files); + eventfs_up_write(eventfs_rwsem); + return ef; +} + +/** + * eventfs_add_dir - add eventfs dir to list to create later + * @name: a pointer to a string containing the name of the file to create. + * @ef_parent: a pointer to the parent eventfs_file for this dir. + * @eventfs_rwsem: a pointer to rw_semaphore + * + * This function adds eventfs dir to list. + * And all these dirs are created on the fly when they are looked up, + * and the dentry and inodes will be removed when they are done. + */ +struct eventfs_file *eventfs_add_dir(const char *name, + struct eventfs_file *ef_parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct eventfs_file *ef; + + if (!ef_parent) + return ERR_PTR(-EINVAL); + + ef = kzalloc(sizeof(*ef), GFP_KERNEL); + if (!ef) + return ERR_PTR(-ENOMEM); + + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); + if (!ef->ei) { + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + INIT_LIST_HEAD(&ef->ei->e_top_files); + + ef->name = kstrdup(name, GFP_KERNEL); + if (!ef->name) { + kfree(ef->ei); + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + ef->mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + ef->iop = &eventfs_root_dir_inode_operations; + ef->fop = &eventfs_file_operations; + ef->created = false; + ef->dentry = NULL; + ef->d_parent = NULL; + ef->data = eventfs_rwsem; + + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ef_parent->ei->e_top_files); + eventfs_up_write(eventfs_rwsem); + return ef; +} diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 999124459..aeca6761f 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -21,6 +21,35 @@ struct file_operations; #ifdef CONFIG_TRACING +struct eventfs_inode { + struct list_head e_top_files; +}; + +struct eventfs_file { + const char *name; + struct dentry *d_parent; + struct dentry *dentry; + struct list_head list; + struct eventfs_inode *ei; + const struct file_operations *fop; + const struct inode_operations *iop; + void *data; + umode_t mode; + bool created; +}; + +struct dentry *eventfs_create_events_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem); + +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem); + +struct eventfs_file *eventfs_add_dir(const char *name, + struct eventfs_file *ef_parent, + struct rw_semaphore *eventfs_rwsem); + struct dentry *tracefs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 616e1aa1c..3726725c8 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -359,6 +359,7 @@ struct trace_array { struct dentry *options; struct dentry *percpu_dir; struct dentry *event_dir; + struct rw_semaphore eventfs_rwsem; struct trace_options *topts; struct list_head systems; struct list_head events;