From 834bf76add3e6168038150f162cbccf1fd492a67 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Mon, 22 Jan 2024 15:27:48 -0500 Subject: eventfs: Save directory inodes in the eventfs_inode structure The eventfs inodes and directories are allocated when referenced. But this leaves the issue of keeping consistent inode numbers and the number is only saved in the inode structure itself. When the inode is no longer referenced, it can be freed. When the file that the inode was representing is referenced again, the inode is once again created, but the inode number needs to be the same as it was before. Just making the inode numbers the same for all files is fine, but that does not work with directories. The find command will check for loops via the inode number and having the same inode number for directories triggers: # find /sys/kernel/tracing find: File system loop detected; '/sys/kernel/debug/tracing/events/initcall/initcall_finish' is part of the same file system loop as '/sys/kernel/debug/tracing/events/initcall'. [..] Linus pointed out that the eventfs_inode structure ends with a single 32bit int, and on 64 bit machines, there's likely a 4 byte hole due to alignment. We can use this hole to store the inode number for the eventfs_inode. All directories in eventfs are represented by an eventfs_inode and that data structure can hold its inode number. That last int was also purposely placed at the end of the structure to prevent holes from within. Now that there's a 4 byte number to hold the inode, both the inode number and the last integer can be moved up in the structure for better cache locality, where the llist and rcu fields can be moved to the end as they are only used when the eventfs_inode is being deleted. Link: https://lore.kernel.org/all/CAMuHMdXKiorg-jiuKoZpfZyDJ3Ynrfb8=X+c7x0Eewxn-YRdCA@mail.gmail.com/ Link: https://lore.kernel.org/linux-trace-kernel/20240122152748.46897388@gandalf.local.home Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Linus Torvalds Reported-by: Geert Uytterhoeven Tested-by: Geert Uytterhoeven Fixes: 53c41052ba31 ("eventfs: Have the inodes all for files and directories all be the same") Signed-off-by: Steven Rostedt (Google) Reviewed-by: Kees Cook --- fs/tracefs/internal.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 12b7d0150ae9..45397df9bb65 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -55,6 +55,10 @@ struct eventfs_inode { struct eventfs_attr *entry_attrs; struct eventfs_attr attr; void *data; + unsigned int is_freed:1; + unsigned int is_events:1; + unsigned int nr_entries:30; + unsigned int ino; /* * Union - used for deletion * @llist: for calling dput() if needed after RCU @@ -64,9 +68,6 @@ struct eventfs_inode { struct llist_node llist; struct rcu_head rcu; }; - unsigned int is_freed:1; - unsigned int is_events:1; - unsigned int nr_entries:30; }; static inline struct tracefs_inode *get_tracefs(const struct inode *inode) -- cgit v1.2.3 From 29142dc92c37d3259a33aef15b03e6ee25b0d188 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 27 Jan 2024 13:21:14 -0800 Subject: tracefs: remove stale 'update_gid' code The 'eventfs_update_gid()' function is no longer called, so remove it (and the helper function it uses). Link: https://lore.kernel.org/all/CAHk-=wj+DsZZ=2iTUkJ-Nojs9fjYMvPs1NuoM3yK7aTDtJfPYQ@mail.gmail.com/ Fixes: 8186fff7ab64 ("tracefs/eventfs: Use root and instance inodes as default ownership") Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 38 -------------------------------------- fs/tracefs/internal.h | 1 - 2 files changed, 39 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 6b211522a13e..1c3dd0ad4660 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -281,44 +281,6 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode, inode->i_gid = attr->gid; } -static void update_gid(struct eventfs_inode *ei, kgid_t gid, int level) -{ - struct eventfs_inode *ei_child; - - /* at most we have events/system/event */ - if (WARN_ON_ONCE(level > 3)) - return; - - ei->attr.gid = gid; - - if (ei->entry_attrs) { - for (int i = 0; i < ei->nr_entries; i++) { - ei->entry_attrs[i].gid = gid; - } - } - - /* - * Only eventfs_inode with dentries are updated, make sure - * all eventfs_inodes are updated. If one of the children - * do not have a dentry, this function must traverse it. - */ - list_for_each_entry_srcu(ei_child, &ei->children, list, - srcu_read_lock_held(&eventfs_srcu)) { - if (!ei_child->dentry) - update_gid(ei_child, gid, level + 1); - } -} - -void eventfs_update_gid(struct dentry *dentry, kgid_t gid) -{ - struct eventfs_inode *ei = dentry->d_fsdata; - int idx; - - idx = srcu_read_lock(&eventfs_srcu); - update_gid(ei, gid, 0); - srcu_read_unlock(&eventfs_srcu, idx); -} - /** * create_file - create a file in the tracefs filesystem * @name: the name of the file to create. diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 45397df9bb65..91c2bf0b91d9 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -82,7 +82,6 @@ struct inode *tracefs_get_inode(struct super_block *sb); struct dentry *eventfs_start_creating(const char *name, struct dentry *parent); struct dentry *eventfs_failed_creating(struct dentry *dentry); struct dentry *eventfs_end_creating(struct dentry *dentry); -void eventfs_update_gid(struct dentry *dentry, kgid_t gid); void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry); #endif /* _TRACEFS_INTERNAL_H */ -- cgit v1.2.3 From d81786f53aec14fd4d56263145a0635afbc64617 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Wed, 31 Jan 2024 13:49:19 -0500 Subject: tracefs: Zero out the tracefs_inode when allocating it eventfs uses the tracefs_inode and assumes that it's already initialized to zero. That is, it doesn't set fields to zero (like ti->private) after getting its tracefs_inode. This causes bugs due to stale values. Just initialize the entire structure to zero on allocation so there isn't any more surprises. This is a partial fix to access to ti->private. The assignment still needs to be made before the dentry is instantiated. Link: https://lore.kernel.org/linux-trace-kernel/20240131185512.315825944@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Christian Brauner Cc: Al Viro Cc: Ajay Kaher Cc: Greg Kroah-Hartman Fixes: 5790b1fb3d672 ("eventfs: Remove eventfs_file and just use eventfs_inode") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202401291043.e62e89dc-oliver.sang@intel.com Suggested-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/inode.c | 6 ++++-- fs/tracefs/internal.h | 3 ++- 2 files changed, 6 insertions(+), 3 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index e1b172c0e091..888e42087847 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -38,8 +38,6 @@ static struct inode *tracefs_alloc_inode(struct super_block *sb) if (!ti) return NULL; - ti->flags = 0; - return &ti->vfs_inode; } @@ -779,7 +777,11 @@ static void init_once(void *foo) { struct tracefs_inode *ti = (struct tracefs_inode *) foo; + /* inode_init_once() calls memset() on the vfs_inode portion */ inode_init_once(&ti->vfs_inode); + + /* Zero out the rest */ + memset_after(ti, 0, vfs_inode); } static int __init tracefs_init(void) diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 91c2bf0b91d9..7d84349ade87 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -11,9 +11,10 @@ enum { }; struct tracefs_inode { + struct inode vfs_inode; + /* The below gets initialized with memset_after(ti, 0, vfs_inode) */ unsigned long flags; void *private; - struct inode vfs_inode; }; /* -- cgit v1.2.3 From 49304c2b93e4f7468b51ef717cbe637981397115 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 31 Jan 2024 23:32:27 -0500 Subject: tracefs: dentry lookup crapectomy The dentry lookup for eventfs files was very broken, and had lots of signs of the old situation where the filesystem names were all created statically in the dentry tree, rather than being looked up dynamically based on the eventfs data structures. You could see it in the naming - how it claimed to "create" dentries rather than just look up the dentries that were given it. You could see it in various nonsensical and very incorrect operations, like using "simple_lookup()" on the dentries that were passed in, which only results in those dentries becoming negative dentries. Which meant that any other lookup would possibly return ENOENT if it saw that negative dentry before the data was then later filled in. You could see it in the immense amount of nonsensical code that didn't actually just do lookups. Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/ Link: https://lore.kernel.org/linux-trace-kernel/20240131233227.73db55e1@gandalf.local.home Cc: stable@vger.kernel.org Cc: Al Viro Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Christian Brauner Cc: Greg Kroah-Hartman Cc: Ajay Kaher Cc: Mark Rutland Fixes: c1504e510238 ("eventfs: Implement eventfs dir creation functions") Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 275 +++++++++-------------------------------------- fs/tracefs/inode.c | 69 ------------ fs/tracefs/internal.h | 3 - 3 files changed, 50 insertions(+), 297 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index e9819d719d2a..04c2ab90f93e 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -230,7 +230,6 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry) { struct eventfs_inode *ei; - mutex_lock(&eventfs_mutex); do { // The parent is stable because we do not do renames dentry = dentry->d_parent; @@ -247,7 +246,6 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry) } // Walk upwards until you find the events inode } while (!ei->is_events); - mutex_unlock(&eventfs_mutex); update_top_events_attr(ei, dentry->d_sb); @@ -280,11 +278,10 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode, } /** - * create_file - create a file in the tracefs filesystem - * @name: the name of the file to create. + * lookup_file - look up a file in the tracefs filesystem + * @dentry: the dentry to look up * @mode: the permission that the file should have. * @attr: saved attributes changed by user - * @parent: parent dentry for this file. * @data: something that the caller will want to get to later on. * @fop: struct file_operations that should be used for this file. * @@ -292,13 +289,13 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode, * directory. The inode.i_private pointer will point to @data in the open() * call. */ -static struct dentry *create_file(const char *name, umode_t mode, +static struct dentry *lookup_file(struct dentry *dentry, + umode_t mode, struct eventfs_attr *attr, - struct dentry *parent, void *data, + void *data, const struct file_operations *fop) { struct tracefs_inode *ti; - struct dentry *dentry; struct inode *inode; if (!(mode & S_IFMT)) @@ -307,15 +304,9 @@ static struct dentry *create_file(const char *name, umode_t mode, if (WARN_ON_ONCE(!S_ISREG(mode))) return NULL; - WARN_ON_ONCE(!parent); - dentry = eventfs_start_creating(name, parent); - - if (IS_ERR(dentry)) - return dentry; - inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) - return eventfs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); /* If the user updated the directory's attributes, use them */ update_inode_attr(dentry, inode, attr, mode); @@ -329,32 +320,29 @@ static struct dentry *create_file(const char *name, umode_t mode, ti = get_tracefs(inode); ti->flags |= TRACEFS_EVENT_INODE; - d_instantiate(dentry, inode); + + d_add(dentry, inode); fsnotify_create(dentry->d_parent->d_inode, dentry); - return eventfs_end_creating(dentry); + return dentry; }; /** - * create_dir - create a dir in the tracefs filesystem + * lookup_dir_entry - look up a dir in the tracefs filesystem + * @dentry: the directory to look up * @ei: the eventfs_inode that represents the directory to create - * @parent: parent dentry for this file. * - * This function will create a dentry for a directory represented by + * This function will look up a dentry for a directory represented by * a eventfs_inode. */ -static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent) +static struct dentry *lookup_dir_entry(struct dentry *dentry, + struct eventfs_inode *pei, struct eventfs_inode *ei) { struct tracefs_inode *ti; - struct dentry *dentry; struct inode *inode; - dentry = eventfs_start_creating(ei->name, parent); - if (IS_ERR(dentry)) - return dentry; - inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) - return eventfs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); /* If the user updated the directory's attributes, use them */ update_inode_attr(dentry, inode, &ei->attr, @@ -371,11 +359,14 @@ static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent /* Only directories have ti->private set to an ei, not files */ ti->private = ei; + dentry->d_fsdata = ei; + ei->dentry = dentry; // Remove me! + inc_nlink(inode); - d_instantiate(dentry, inode); + d_add(dentry, inode); inc_nlink(dentry->d_parent->d_inode); fsnotify_mkdir(dentry->d_parent->d_inode, dentry); - return eventfs_end_creating(dentry); + return dentry; } static void free_ei(struct eventfs_inode *ei) @@ -425,7 +416,7 @@ void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry) } /** - * create_file_dentry - create a dentry for a file of an eventfs_inode + * lookup_file_dentry - create a dentry for a file of an eventfs_inode * @ei: the eventfs_inode that the file will be created under * @idx: the index into the d_children[] of the @ei * @parent: The parent dentry of the created file. @@ -438,157 +429,21 @@ void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry) * address located at @e_dentry. */ static struct dentry * -create_file_dentry(struct eventfs_inode *ei, int idx, - struct dentry *parent, const char *name, umode_t mode, void *data, +lookup_file_dentry(struct dentry *dentry, + struct eventfs_inode *ei, int idx, + umode_t mode, void *data, const struct file_operations *fops) { struct eventfs_attr *attr = NULL; struct dentry **e_dentry = &ei->d_children[idx]; - struct dentry *dentry; - - WARN_ON_ONCE(!inode_is_locked(parent->d_inode)); - mutex_lock(&eventfs_mutex); - if (ei->is_freed) { - mutex_unlock(&eventfs_mutex); - return NULL; - } - /* If the e_dentry already has a dentry, use it */ - if (*e_dentry) { - dget(*e_dentry); - mutex_unlock(&eventfs_mutex); - return *e_dentry; - } - - /* ei->entry_attrs are protected by SRCU */ if (ei->entry_attrs) attr = &ei->entry_attrs[idx]; - mutex_unlock(&eventfs_mutex); - - dentry = create_file(name, mode, attr, parent, data, fops); + dentry->d_fsdata = ei; // NOTE: ei of _parent_ + lookup_file(dentry, mode, attr, data, fops); - mutex_lock(&eventfs_mutex); - - if (IS_ERR_OR_NULL(dentry)) { - /* - * When the mutex was released, something else could have - * created the dentry for this e_dentry. In which case - * use that one. - * - * If ei->is_freed is set, the e_dentry is currently on its - * way to being freed, don't return it. If e_dentry is NULL - * it means it was already freed. - */ - if (ei->is_freed) { - dentry = NULL; - } else { - dentry = *e_dentry; - dget(dentry); - } - mutex_unlock(&eventfs_mutex); - return dentry; - } - - if (!*e_dentry && !ei->is_freed) { - *e_dentry = dentry; - dentry->d_fsdata = ei; - } else { - /* - * Should never happen unless we get here due to being freed. - * Otherwise it means two dentries exist with the same name. - */ - WARN_ON_ONCE(!ei->is_freed); - dentry = NULL; - } - mutex_unlock(&eventfs_mutex); - - return dentry; -} - -/** - * eventfs_post_create_dir - post create dir routine - * @ei: eventfs_inode of recently created dir - * - * Map the meta-data of files within an eventfs dir to their parent dentry - */ -static void eventfs_post_create_dir(struct eventfs_inode *ei) -{ - struct eventfs_inode *ei_child; - - lockdep_assert_held(&eventfs_mutex); - - /* srcu lock already held */ - /* fill parent-child relation */ - list_for_each_entry_srcu(ei_child, &ei->children, list, - srcu_read_lock_held(&eventfs_srcu)) { - ei_child->d_parent = ei->dentry; - } -} - -/** - * create_dir_dentry - Create a directory dentry for the eventfs_inode - * @pei: The eventfs_inode parent of ei. - * @ei: The eventfs_inode to create the directory for - * @parent: The dentry of the parent of this directory - * - * This creates and attaches a directory dentry to the eventfs_inode @ei. - */ -static struct dentry * -create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, - struct dentry *parent) -{ - struct dentry *dentry = NULL; - - WARN_ON_ONCE(!inode_is_locked(parent->d_inode)); - - mutex_lock(&eventfs_mutex); - if (pei->is_freed || ei->is_freed) { - mutex_unlock(&eventfs_mutex); - return NULL; - } - if (ei->dentry) { - /* If the eventfs_inode already has a dentry, use it */ - dentry = ei->dentry; - dget(dentry); - mutex_unlock(&eventfs_mutex); - return dentry; - } - mutex_unlock(&eventfs_mutex); - - dentry = create_dir(ei, parent); - - mutex_lock(&eventfs_mutex); - - if (IS_ERR_OR_NULL(dentry) && !ei->is_freed) { - /* - * When the mutex was released, something else could have - * created the dentry for this e_dentry. In which case - * use that one. - * - * If ei->is_freed is set, the e_dentry is currently on its - * way to being freed. - */ - dentry = ei->dentry; - if (dentry) - dget(dentry); - mutex_unlock(&eventfs_mutex); - return dentry; - } - - if (!ei->dentry && !ei->is_freed) { - ei->dentry = dentry; - eventfs_post_create_dir(ei); - dentry->d_fsdata = ei; - } else { - /* - * Should never happen unless we get here due to being freed. - * Otherwise it means two dentries exist with the same name. - */ - WARN_ON_ONCE(!ei->is_freed); - dentry = NULL; - } - mutex_unlock(&eventfs_mutex); + *e_dentry = dentry; // Remove me return dentry; } @@ -607,79 +462,49 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { - const struct file_operations *fops; - const struct eventfs_entry *entry; struct eventfs_inode *ei_child; struct tracefs_inode *ti; struct eventfs_inode *ei; - struct dentry *ei_dentry = NULL; - struct dentry *ret = NULL; - struct dentry *d; const char *name = dentry->d_name.name; - umode_t mode; - void *data; - int idx; - int i; - int r; ti = get_tracefs(dir); if (!(ti->flags & TRACEFS_EVENT_INODE)) - return NULL; - - /* Grab srcu to prevent the ei from going away */ - idx = srcu_read_lock(&eventfs_srcu); + return ERR_PTR(-EIO); - /* - * Grab the eventfs_mutex to consistent value from ti->private. - * This s - */ mutex_lock(&eventfs_mutex); - ei = READ_ONCE(ti->private); - if (ei && !ei->is_freed) - ei_dentry = READ_ONCE(ei->dentry); - mutex_unlock(&eventfs_mutex); - if (!ei || !ei_dentry) + ei = ti->private; + if (!ei || ei->is_freed) goto out; - data = ei->data; - - list_for_each_entry_srcu(ei_child, &ei->children, list, - srcu_read_lock_held(&eventfs_srcu)) { + list_for_each_entry(ei_child, &ei->children, list) { if (strcmp(ei_child->name, name) != 0) continue; - ret = simple_lookup(dir, dentry, flags); - if (IS_ERR(ret)) + if (ei_child->is_freed) goto out; - d = create_dir_dentry(ei, ei_child, ei_dentry); - dput(d); + lookup_dir_entry(dentry, ei, ei_child); goto out; } - for (i = 0; i < ei->nr_entries; i++) { - entry = &ei->entries[i]; - if (strcmp(name, entry->name) == 0) { - void *cdata = data; - mutex_lock(&eventfs_mutex); - /* If ei->is_freed, then the event itself may be too */ - if (!ei->is_freed) - r = entry->callback(name, &mode, &cdata, &fops); - else - r = -1; - mutex_unlock(&eventfs_mutex); - if (r <= 0) - continue; - ret = simple_lookup(dir, dentry, flags); - if (IS_ERR(ret)) - goto out; - d = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops); - dput(d); - break; - } + for (int i = 0; i < ei->nr_entries; i++) { + void *data; + umode_t mode; + const struct file_operations *fops; + const struct eventfs_entry *entry = &ei->entries[i]; + + if (strcmp(name, entry->name) != 0) + continue; + + data = ei->data; + if (entry->callback(name, &mode, &data, &fops) <= 0) + goto out; + + lookup_file_dentry(dentry, ei, i, mode, data, fops); + goto out; } out: - srcu_read_unlock(&eventfs_srcu, idx); - return ret; + mutex_unlock(&eventfs_mutex); + return NULL; } /* diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 888e42087847..5c84460feeeb 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -495,75 +495,6 @@ struct dentry *tracefs_end_creating(struct dentry *dentry) return dentry; } -/** - * eventfs_start_creating - start the process of creating a dentry - * @name: Name of the file created for the dentry - * @parent: The parent dentry where this dentry will be created - * - * This is a simple helper function for the dynamically created eventfs - * files. When the directory of the eventfs files are accessed, their - * dentries are created on the fly. This function is used to start that - * process. - */ -struct dentry *eventfs_start_creating(const char *name, struct dentry *parent) -{ - struct dentry *dentry; - int error; - - /* Must always have a parent. */ - if (WARN_ON_ONCE(!parent)) - return ERR_PTR(-EINVAL); - - error = simple_pin_fs(&trace_fs_type, &tracefs_mount, - &tracefs_mount_count); - if (error) - return ERR_PTR(error); - - if (unlikely(IS_DEADDIR(parent->d_inode))) - dentry = ERR_PTR(-ENOENT); - else - dentry = lookup_one_len(name, parent, strlen(name)); - - if (!IS_ERR(dentry) && dentry->d_inode) { - dput(dentry); - dentry = ERR_PTR(-EEXIST); - } - - if (IS_ERR(dentry)) - simple_release_fs(&tracefs_mount, &tracefs_mount_count); - - return dentry; -} - -/** - * eventfs_failed_creating - clean up a failed eventfs dentry creation - * @dentry: The dentry to clean up - * - * If after calling eventfs_start_creating(), a failure is detected, the - * resources created by eventfs_start_creating() needs to be cleaned up. In - * that case, this function should be called to perform that clean up. - */ -struct dentry *eventfs_failed_creating(struct dentry *dentry) -{ - dput(dentry); - simple_release_fs(&tracefs_mount, &tracefs_mount_count); - return NULL; -} - -/** - * eventfs_end_creating - Finish the process of creating a eventfs dentry - * @dentry: The dentry that has successfully been created. - * - * This function is currently just a place holder to match - * eventfs_start_creating(). In case any synchronization needs to be added, - * this function will be used to implement that without having to modify - * the callers of eventfs_start_creating(). - */ -struct dentry *eventfs_end_creating(struct dentry *dentry) -{ - return dentry; -} - /* Find the inode that this will use for default */ static struct inode *instance_inode(struct dentry *parent, struct inode *inode) { diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 7d84349ade87..09037e2c173d 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -80,9 +80,6 @@ struct dentry *tracefs_start_creating(const char *name, struct dentry *parent); struct dentry *tracefs_end_creating(struct dentry *dentry); struct dentry *tracefs_failed_creating(struct dentry *dentry); struct inode *tracefs_get_inode(struct super_block *sb); -struct dentry *eventfs_start_creating(const char *name, struct dentry *parent); -struct dentry *eventfs_failed_creating(struct dentry *dentry); -struct dentry *eventfs_end_creating(struct dentry *dentry); void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry); #endif /* _TRACEFS_INTERNAL_H */ -- cgit v1.2.3 From 408600be78cdb8c650a97ecc7ff411cb216811b5 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 31 Jan 2024 13:49:23 -0500 Subject: eventfs: Remove unused d_parent pointer field It's never used Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/ Link: https://lore.kernel.org/linux-trace-kernel/20240131185512.961772428@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Christian Brauner Cc: Al Viro Cc: Ajay Kaher Cc: Greg Kroah-Hartman Fixes: c1504e510238 ("eventfs: Implement eventfs dir creation functions") Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 4 +--- fs/tracefs/internal.h | 2 -- 2 files changed, 1 insertion(+), 5 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 04c2ab90f93e..16ca8d9759b1 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -680,10 +680,8 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode INIT_LIST_HEAD(&ei->list); mutex_lock(&eventfs_mutex); - if (!parent->is_freed) { + if (!parent->is_freed) list_add_tail(&ei->list, &parent->children); - ei->d_parent = parent->dentry; - } mutex_unlock(&eventfs_mutex); /* Was the parent freed? */ diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 09037e2c173d..932733a2696a 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -36,7 +36,6 @@ struct eventfs_attr { * @name: the name of the directory to create * @children: link list into the child eventfs_inode * @dentry: the dentry of the directory - * @d_parent: pointer to the parent's dentry * @d_children: The array of dentries to represent the files when created * @entry_attrs: Saved mode and ownership of the @d_children * @attr: Saved mode and ownership of eventfs_inode itself @@ -51,7 +50,6 @@ struct eventfs_inode { const char *name; struct list_head children; struct dentry *dentry; /* Check is_freed to access */ - struct dentry *d_parent; struct dentry **d_children; struct eventfs_attr *entry_attrs; struct eventfs_attr attr; -- cgit v1.2.3 From 8dce06e98c70a7fcbb4bca7d90faf40522e65c58 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 31 Jan 2024 13:49:24 -0500 Subject: eventfs: Clean up dentry ops and add revalidate function In order for the dentries to stay up-to-date with the eventfs changes, just add a 'd_revalidate' function that checks the 'is_freed' bit. Also, clean up the dentry release to actually use d_release() rather than the slightly odd d_iput() function. We don't care about the inode, all we want to do is to get rid of the refcount to the eventfs data added by dentry->d_fsdata. It would probably be cleaner to make eventfs its own filesystem, or at least set its own dentry ops when looking up eventfs files. But as it is, only eventfs dentries use d_fsdata, so we don't really need to split these things up by use. Another thing that might be worth doing is to make all eventfs lookups mark their dentries as not worth caching. We could do that with d_delete(), but the DCACHE_DONTCACHE flag would likely be even better. As it is, the dentries are all freeable, but they only tend to get freed at memory pressure rather than more proactively. But that's a separate issue. Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/ Link: https://lore.kernel.org/linux-trace-kernel/20240131185513.124644253@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Christian Brauner Cc: Al Viro Cc: Ajay Kaher Cc: Greg Kroah-Hartman Fixes: c1504e510238 ("eventfs: Implement eventfs dir creation functions") Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 5 ++--- fs/tracefs/inode.c | 27 ++++++++++++++++++--------- fs/tracefs/internal.h | 3 ++- 3 files changed, 22 insertions(+), 13 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 16ca8d9759b1..b2285d5f3fed 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -378,13 +378,12 @@ static void free_ei(struct eventfs_inode *ei) } /** - * eventfs_set_ei_status_free - remove the dentry reference from an eventfs_inode - * @ti: the tracefs_inode of the dentry + * eventfs_d_release - dentry is going away * @dentry: dentry which has the reference to remove. * * Remove the association between a dentry from an eventfs_inode. */ -void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry) +void eventfs_d_release(struct dentry *dentry) { struct eventfs_inode *ei; int i; diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 5c84460feeeb..d65ffad4c327 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -377,21 +377,30 @@ static const struct super_operations tracefs_super_operations = { .show_options = tracefs_show_options, }; -static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode) +/* + * It would be cleaner if eventfs had its own dentry ops. + * + * Note that d_revalidate is called potentially under RCU, + * so it can't take the eventfs mutex etc. It's fine - if + * we open a file just as it's marked dead, things will + * still work just fine, and just see the old stale case. + */ +static void tracefs_d_release(struct dentry *dentry) { - struct tracefs_inode *ti; + if (dentry->d_fsdata) + eventfs_d_release(dentry); +} - if (!dentry || !inode) - return; +static int tracefs_d_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct eventfs_inode *ei = dentry->d_fsdata; - ti = get_tracefs(inode); - if (ti && ti->flags & TRACEFS_EVENT_INODE) - eventfs_set_ei_status_free(ti, dentry); - iput(inode); + return !(ei && ei->is_freed); } static const struct dentry_operations tracefs_dentry_operations = { - .d_iput = tracefs_dentry_iput, + .d_revalidate = tracefs_d_revalidate, + .d_release = tracefs_d_release, }; static int trace_fill_super(struct super_block *sb, void *data, int silent) diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 932733a2696a..4b50a0668055 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -78,6 +78,7 @@ struct dentry *tracefs_start_creating(const char *name, struct dentry *parent); struct dentry *tracefs_end_creating(struct dentry *dentry); struct dentry *tracefs_failed_creating(struct dentry *dentry); struct inode *tracefs_get_inode(struct super_block *sb); -void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry); + +void eventfs_d_release(struct dentry *dentry); #endif /* _TRACEFS_INTERNAL_H */ -- cgit v1.2.3 From 43aa6f97c2d03a52c1ddb86768575fc84344bdbb Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 31 Jan 2024 13:49:25 -0500 Subject: eventfs: Get rid of dentry pointers without refcounts The eventfs inode had pointers to dentries (and child dentries) without actually holding a refcount on said pointer. That is fundamentally broken, and while eventfs tried to then maintain coherence with dentries going away by hooking into the '.d_iput' callback, that doesn't actually work since it's not ordered wrt lookups. There were two reasonms why eventfs tried to keep a pointer to a dentry: - the creation of a 'events' directory would actually have a stable dentry pointer that it created with tracefs_start_creating(). And it needed that dentry when tearing it all down again in eventfs_remove_events_dir(). This use is actually ok, because the special top-level events directory dentries are actually stable, not just a temporary cache of the eventfs data structures. - the 'eventfs_inode' (aka ei) needs to stay around as long as there are dentries that refer to it. It then used these dentry pointers as a replacement for doing reference counting: it would try to make sure that there was only ever one dentry associated with an event_inode, and keep a child dentry array around to see which dentries might still refer to the parent ei. This gets rid of the invalid dentry pointer use, and renames the one valid case to a different name to make it clear that it's not just any random dentry. The magic child dentry array that is kind of a "reverse reference list" is simply replaced by having child dentries take a ref to the ei. As does the directory dentries. That makes the broken use case go away. Link: https://lore.kernel.org/linux-trace-kernel/202401291043.e62e89dc-oliver.sang@intel.com/ Link: https://lore.kernel.org/linux-trace-kernel/20240131185513.280463000@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Christian Brauner Cc: Al Viro Cc: Ajay Kaher Cc: Greg Kroah-Hartman Fixes: c1504e510238 ("eventfs: Implement eventfs dir creation functions") Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 248 ++++++++++++++--------------------------------- fs/tracefs/internal.h | 7 +- 2 files changed, 78 insertions(+), 177 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index b2285d5f3fed..515fdace1eea 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -62,6 +62,35 @@ enum { #define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) +/* + * eventfs_inode reference count management. + * + * NOTE! We count only references from dentries, in the + * form 'dentry->d_fsdata'. There are also references from + * directory inodes ('ti->private'), but the dentry reference + * count is always a superset of the inode reference count. + */ +static void release_ei(struct kref *ref) +{ + struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref); + kfree(ei->entry_attrs); + kfree_const(ei->name); + kfree_rcu(ei, rcu); +} + +static inline void put_ei(struct eventfs_inode *ei) +{ + if (ei) + kref_put(&ei->kref, release_ei); +} + +static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei) +{ + if (ei) + kref_get(&ei->kref); + return ei; +} + static struct dentry *eventfs_root_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags); @@ -289,7 +318,8 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode, * directory. The inode.i_private pointer will point to @data in the open() * call. */ -static struct dentry *lookup_file(struct dentry *dentry, +static struct dentry *lookup_file(struct eventfs_inode *parent_ei, + struct dentry *dentry, umode_t mode, struct eventfs_attr *attr, void *data, @@ -302,7 +332,7 @@ static struct dentry *lookup_file(struct dentry *dentry, mode |= S_IFREG; if (WARN_ON_ONCE(!S_ISREG(mode))) - return NULL; + return ERR_PTR(-EIO); inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) @@ -321,9 +351,12 @@ static struct dentry *lookup_file(struct dentry *dentry, ti = get_tracefs(inode); ti->flags |= TRACEFS_EVENT_INODE; + // Files have their parent's ei as their fsdata + dentry->d_fsdata = get_ei(parent_ei); + d_add(dentry, inode); fsnotify_create(dentry->d_parent->d_inode, dentry); - return dentry; + return NULL; }; /** @@ -359,22 +392,29 @@ static struct dentry *lookup_dir_entry(struct dentry *dentry, /* Only directories have ti->private set to an ei, not files */ ti->private = ei; - dentry->d_fsdata = ei; - ei->dentry = dentry; // Remove me! + dentry->d_fsdata = get_ei(ei); inc_nlink(inode); d_add(dentry, inode); inc_nlink(dentry->d_parent->d_inode); fsnotify_mkdir(dentry->d_parent->d_inode, dentry); - return dentry; + return NULL; } -static void free_ei(struct eventfs_inode *ei) +static inline struct eventfs_inode *alloc_ei(const char *name) { - kfree_const(ei->name); - kfree(ei->d_children); - kfree(ei->entry_attrs); - kfree(ei); + struct eventfs_inode *ei = kzalloc(sizeof(*ei), GFP_KERNEL); + + if (!ei) + return NULL; + + ei->name = kstrdup_const(name, GFP_KERNEL); + if (!ei->name) { + kfree(ei); + return NULL; + } + kref_init(&ei->kref); + return ei; } /** @@ -385,39 +425,13 @@ static void free_ei(struct eventfs_inode *ei) */ void eventfs_d_release(struct dentry *dentry) { - struct eventfs_inode *ei; - int i; - - mutex_lock(&eventfs_mutex); - - ei = dentry->d_fsdata; - if (!ei) - goto out; - - /* This could belong to one of the files of the ei */ - if (ei->dentry != dentry) { - for (i = 0; i < ei->nr_entries; i++) { - if (ei->d_children[i] == dentry) - break; - } - if (WARN_ON_ONCE(i == ei->nr_entries)) - goto out; - ei->d_children[i] = NULL; - } else if (ei->is_freed) { - free_ei(ei); - } else { - ei->dentry = NULL; - } - - dentry->d_fsdata = NULL; - out: - mutex_unlock(&eventfs_mutex); + put_ei(dentry->d_fsdata); } /** * lookup_file_dentry - create a dentry for a file of an eventfs_inode * @ei: the eventfs_inode that the file will be created under - * @idx: the index into the d_children[] of the @ei + * @idx: the index into the entry_attrs[] of the @ei * @parent: The parent dentry of the created file. * @name: The name of the file to create * @mode: The mode of the file. @@ -434,17 +448,11 @@ lookup_file_dentry(struct dentry *dentry, const struct file_operations *fops) { struct eventfs_attr *attr = NULL; - struct dentry **e_dentry = &ei->d_children[idx]; if (ei->entry_attrs) attr = &ei->entry_attrs[idx]; - dentry->d_fsdata = ei; // NOTE: ei of _parent_ - lookup_file(dentry, mode, attr, data, fops); - - *e_dentry = dentry; // Remove me - - return dentry; + return lookup_file(ei, dentry, mode, attr, data, fops); } /** @@ -465,6 +473,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, struct tracefs_inode *ti; struct eventfs_inode *ei; const char *name = dentry->d_name.name; + struct dentry *result = NULL; ti = get_tracefs(dir); if (!(ti->flags & TRACEFS_EVENT_INODE)) @@ -481,7 +490,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, continue; if (ei_child->is_freed) goto out; - lookup_dir_entry(dentry, ei, ei_child); + result = lookup_dir_entry(dentry, ei, ei_child); goto out; } @@ -498,12 +507,12 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, if (entry->callback(name, &mode, &data, &fops) <= 0) goto out; - lookup_file_dentry(dentry, ei, i, mode, data, fops); + result = lookup_file_dentry(dentry, ei, i, mode, data, fops); goto out; } out: mutex_unlock(&eventfs_mutex); - return NULL; + return result; } /* @@ -653,25 +662,10 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode if (!parent) return ERR_PTR(-EINVAL); - ei = kzalloc(sizeof(*ei), GFP_KERNEL); + ei = alloc_ei(name); if (!ei) return ERR_PTR(-ENOMEM); - ei->name = kstrdup_const(name, GFP_KERNEL); - if (!ei->name) { - kfree(ei); - return ERR_PTR(-ENOMEM); - } - - if (size) { - ei->d_children = kcalloc(size, sizeof(*ei->d_children), GFP_KERNEL); - if (!ei->d_children) { - kfree_const(ei->name); - kfree(ei); - return ERR_PTR(-ENOMEM); - } - } - ei->entries = entries; ei->nr_entries = size; ei->data = data; @@ -685,7 +679,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode /* Was the parent freed? */ if (list_empty(&ei->list)) { - free_ei(ei); + put_ei(ei); ei = NULL; } return ei; @@ -720,28 +714,20 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry if (IS_ERR(dentry)) return ERR_CAST(dentry); - ei = kzalloc(sizeof(*ei), GFP_KERNEL); + ei = alloc_ei(name); if (!ei) - goto fail_ei; + goto fail; inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) goto fail; - if (size) { - ei->d_children = kcalloc(size, sizeof(*ei->d_children), GFP_KERNEL); - if (!ei->d_children) - goto fail; - } - - ei->dentry = dentry; + // Note: we have a ref to the dentry from tracefs_start_creating() + ei->events_dir = dentry; ei->entries = entries; ei->nr_entries = size; ei->is_events = 1; ei->data = data; - ei->name = kstrdup_const(name, GFP_KERNEL); - if (!ei->name) - goto fail; /* Save the ownership of this directory */ uid = d_inode(dentry->d_parent)->i_uid; @@ -772,7 +758,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry inode->i_op = &eventfs_root_dir_inode_operations; inode->i_fop = &eventfs_file_operations; - dentry->d_fsdata = ei; + dentry->d_fsdata = get_ei(ei); /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); @@ -784,72 +770,11 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry return ei; fail: - kfree(ei->d_children); - kfree(ei); - fail_ei: + put_ei(ei); tracefs_failed_creating(dentry); return ERR_PTR(-ENOMEM); } -static LLIST_HEAD(free_list); - -static void eventfs_workfn(struct work_struct *work) -{ - struct eventfs_inode *ei, *tmp; - struct llist_node *llnode; - - llnode = llist_del_all(&free_list); - llist_for_each_entry_safe(ei, tmp, llnode, llist) { - /* This dput() matches the dget() from unhook_dentry() */ - for (int i = 0; i < ei->nr_entries; i++) { - if (ei->d_children[i]) - dput(ei->d_children[i]); - } - /* This should only get here if it had a dentry */ - if (!WARN_ON_ONCE(!ei->dentry)) - dput(ei->dentry); - } -} - -static DECLARE_WORK(eventfs_work, eventfs_workfn); - -static void free_rcu_ei(struct rcu_head *head) -{ - struct eventfs_inode *ei = container_of(head, struct eventfs_inode, rcu); - - if (ei->dentry) { - /* Do not free the ei until all references of dentry are gone */ - if (llist_add(&ei->llist, &free_list)) - queue_work(system_unbound_wq, &eventfs_work); - return; - } - - /* If the ei doesn't have a dentry, neither should its children */ - for (int i = 0; i < ei->nr_entries; i++) { - WARN_ON_ONCE(ei->d_children[i]); - } - - free_ei(ei); -} - -static void unhook_dentry(struct dentry *dentry) -{ - if (!dentry) - return; - /* - * Need to add a reference to the dentry that is expected by - * simple_recursive_removal(), which will include a dput(). - */ - dget(dentry); - - /* - * Also add a reference for the dput() in eventfs_workfn(). - * That is required as that dput() will free the ei after - * the SRCU grace period is over. - */ - dget(dentry); -} - /** * eventfs_remove_rec - remove eventfs dir or file from list * @ei: eventfs_inode to be removed. @@ -862,8 +787,6 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) { struct eventfs_inode *ei_child; - if (!ei) - return; /* * Check recursion depth. It should never be greater than 3: * 0 - events/ @@ -875,28 +798,12 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) return; /* search for nested folders or files */ - list_for_each_entry_srcu(ei_child, &ei->children, list, - lockdep_is_held(&eventfs_mutex)) { - /* Children only have dentry if parent does */ - WARN_ON_ONCE(ei_child->dentry && !ei->dentry); + list_for_each_entry(ei_child, &ei->children, list) eventfs_remove_rec(ei_child, level + 1); - } - ei->is_freed = 1; - - for (int i = 0; i < ei->nr_entries; i++) { - if (ei->d_children[i]) { - /* Children only have dentry if parent does */ - WARN_ON_ONCE(!ei->dentry); - unhook_dentry(ei->d_children[i]); - } - } - - unhook_dentry(ei->dentry); - - list_del_rcu(&ei->list); - call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei); + list_del(&ei->list); + put_ei(ei); } /** @@ -907,22 +814,12 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) */ void eventfs_remove_dir(struct eventfs_inode *ei) { - struct dentry *dentry; - if (!ei) return; mutex_lock(&eventfs_mutex); - dentry = ei->dentry; eventfs_remove_rec(ei, 0); mutex_unlock(&eventfs_mutex); - - /* - * If any of the ei children has a dentry, then the ei itself - * must have a dentry. - */ - if (dentry) - simple_recursive_removal(dentry, NULL); } /** @@ -935,7 +832,11 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei) { struct dentry *dentry; - dentry = ei->dentry; + dentry = ei->events_dir; + if (!dentry) + return; + + ei->events_dir = NULL; eventfs_remove_dir(ei); /* @@ -945,5 +846,6 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei) * sticks around while the other ei->dentry are created * and destroyed dynamically. */ + d_invalidate(dentry); dput(dentry); } diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 4b50a0668055..1886f1826cd8 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -35,8 +35,7 @@ struct eventfs_attr { * @entries: the array of entries representing the files in the directory * @name: the name of the directory to create * @children: link list into the child eventfs_inode - * @dentry: the dentry of the directory - * @d_children: The array of dentries to represent the files when created + * @events_dir: the dentry of the events directory * @entry_attrs: Saved mode and ownership of the @d_children * @attr: Saved mode and ownership of eventfs_inode itself * @data: The private data to pass to the callbacks @@ -45,12 +44,12 @@ struct eventfs_attr { * @nr_entries: The number of items in @entries */ struct eventfs_inode { + struct kref kref; struct list_head list; const struct eventfs_entry *entries; const char *name; struct list_head children; - struct dentry *dentry; /* Check is_freed to access */ - struct dentry **d_children; + struct dentry *events_dir; struct eventfs_attr *entry_attrs; struct eventfs_attr attr; void *data; -- cgit v1.2.3 From 264424dfdd5cbd92bc5b5ddf93944929fc877fac Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Thu, 1 Feb 2024 10:34:48 -0500 Subject: eventfs: Restructure eventfs_inode structure to be more condensed Some of the eventfs_inode structure has holes in it. Rework the structure to be a bit more condensed, and also remove the no longer used llist field. Link: https://lore.kernel.org/linux-trace-kernel/20240201161617.002321438@goodmis.org Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Christian Brauner Cc: Al Viro Cc: Ajay Kaher Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/internal.h | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 1886f1826cd8..beb3dcd0e434 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -32,40 +32,37 @@ struct eventfs_attr { /* * struct eventfs_inode - hold the properties of the eventfs directories. * @list: link list into the parent directory + * @rcu: Union with @list for freeing + * @children: link list into the child eventfs_inode * @entries: the array of entries representing the files in the directory * @name: the name of the directory to create - * @children: link list into the child eventfs_inode * @events_dir: the dentry of the events directory * @entry_attrs: Saved mode and ownership of the @d_children - * @attr: Saved mode and ownership of eventfs_inode itself * @data: The private data to pass to the callbacks + * @attr: Saved mode and ownership of eventfs_inode itself * @is_freed: Flag set if the eventfs is on its way to be freed * Note if is_freed is set, then dentry is corrupted. + * @is_events: Flag set for only the top level "events" directory * @nr_entries: The number of items in @entries + * @ino: The saved inode number */ struct eventfs_inode { - struct kref kref; - struct list_head list; + union { + struct list_head list; + struct rcu_head rcu; + }; + struct list_head children; const struct eventfs_entry *entries; const char *name; - struct list_head children; struct dentry *events_dir; struct eventfs_attr *entry_attrs; - struct eventfs_attr attr; void *data; + struct eventfs_attr attr; + struct kref kref; unsigned int is_freed:1; unsigned int is_events:1; unsigned int nr_entries:30; unsigned int ino; - /* - * Union - used for deletion - * @llist: for calling dput() if needed after RCU - * @rcu: eventfs_inode to delete in RCU - */ - union { - struct llist_node llist; - struct rcu_head rcu; - }; }; static inline struct tracefs_inode *get_tracefs(const struct inode *inode) -- cgit v1.2.3