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Date: Thu, 23 May 2024 17:23:05 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [for-linus][PATCH 7/8] eventfs: Cleanup permissions in creation of inodes
From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
The permissions being set during the creation of the inodes was updating
eventfs_inode attributes as well. Those attributes should only be touched
by the setattr or remount operations, not during the creation of inodes.
The eventfs_inode attributes should only be used to set the inodes and
should not be modified during the inode creation.
Simplify the code and fix the situation by:
1) Removing the eventfs_find_events() and doing a simple lookup for
the events descriptor in eventfs_get_inode()
2) Remove update_events_attr() as the attributes should only be used
to update the inode and should not be modified here.
3) Add update_inode_attr() that uses the attributes to determine what
the inode permissions should be.
4) As the parent_inode of the eventfs_root_inode structure is no longer
needed, remove it.
Now on creation, the inode gets the proper permissions without causing
side effects to the ei->attr field.
Link: https://lore.kernel.org/lkml/20240522165031.944088388@goodmis.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
fs/tracefs/event_inode.c | 90 ++++++++++------------------------------
1 file changed, 23 insertions(+), 67 deletions(-)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index f32c6f7eb29f..320e49056d3a 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -37,7 +37,6 @@ static DEFINE_MUTEX(eventfs_mutex);
struct eventfs_root_inode {
struct eventfs_inode ei;
- struct inode *parent_inode;
struct dentry *events_dir;
};
@@ -229,27 +228,6 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
return ret;
}
-static void update_events_attr(struct eventfs_inode *ei, struct super_block *sb)
-{
- struct eventfs_root_inode *rei;
- struct inode *parent;
-
- rei = get_root_inode(ei);
-
- /* Use the parent inode permissions unless root set its permissions */
- parent = rei->parent_inode;
-
- if (rei->ei.attr.mode & EVENTFS_SAVE_UID)
- ei->attr.uid = rei->ei.attr.uid;
- else
- ei->attr.uid = parent->i_uid;
-
- if (rei->ei.attr.mode & EVENTFS_SAVE_GID)
- ei->attr.gid = rei->ei.attr.gid;
- else
- ei->attr.gid = parent->i_gid;
-}
-
static const struct inode_operations eventfs_dir_inode_operations = {
.lookup = eventfs_root_lookup,
.setattr = eventfs_set_attr,
@@ -321,60 +299,30 @@ void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid)
update_gid, ti->vfs_inode.i_gid, 0);
}
-/* Return the evenfs_inode of the "events" directory */
-static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
+static void update_inode_attr(struct inode *inode, umode_t mode,
+ struct eventfs_attr *attr, struct eventfs_root_inode *rei)
{
- struct eventfs_inode *ei;
-
- do {
- // The parent is stable because we do not do renames
- dentry = dentry->d_parent;
- // ... and directories always have d_fsdata
- ei = dentry->d_fsdata;
-
- /*
- * If the ei is being freed, the ownership of the children
- * doesn't matter.
- */
- if (ei->is_freed)
- return NULL;
-
- // Walk upwards until you find the events inode
- } while (!ei->is_events);
-
- update_events_attr(ei, dentry->d_sb);
-
- return ei;
-}
-
-static void update_inode_attr(struct dentry *dentry, struct inode *inode,
- struct eventfs_attr *attr, umode_t mode)
-{
- struct eventfs_inode *events_ei = eventfs_find_events(dentry);
-
- if (!events_ei)
- return;
-
- inode->i_mode = mode;
- inode->i_uid = events_ei->attr.uid;
- inode->i_gid = events_ei->attr.gid;
-
- if (!attr)
- return;
-
- if (attr->mode & EVENTFS_SAVE_MODE)
+ if (attr && attr->mode & EVENTFS_SAVE_MODE)
inode->i_mode = attr->mode & EVENTFS_MODE_MASK;
+ else
+ inode->i_mode = mode;
- if (attr->mode & EVENTFS_SAVE_UID)
+ if (attr && attr->mode & EVENTFS_SAVE_UID)
inode->i_uid = attr->uid;
+ else
+ inode->i_uid = rei->ei.attr.uid;
- if (attr->mode & EVENTFS_SAVE_GID)
+ if (attr && attr->mode & EVENTFS_SAVE_GID)
inode->i_gid = attr->gid;
+ else
+ inode->i_gid = rei->ei.attr.gid;
}
static struct inode *eventfs_get_inode(struct dentry *dentry, struct eventfs_attr *attr,
umode_t mode, struct eventfs_inode *ei)
{
+ struct eventfs_root_inode *rei;
+ struct eventfs_inode *pei;
struct tracefs_inode *ti;
struct inode *inode;
@@ -386,7 +334,16 @@ static struct inode *eventfs_get_inode(struct dentry *dentry, struct eventfs_att
ti->private = ei;
ti->flags |= TRACEFS_EVENT_INODE;
- update_inode_attr(dentry, inode, attr, mode);
+ /* Find the top dentry that holds the "events" directory */
+ do {
+ dentry = dentry->d_parent;
+ /* Directories always have d_fsdata */
+ pei = dentry->d_fsdata;
+ } while (!pei->is_events);
+
+ rei = get_root_inode(pei);
+
+ update_inode_attr(inode, mode, attr, rei);
return inode;
}
@@ -823,7 +780,6 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
// Note: we have a ref to the dentry from tracefs_start_creating()
rei = get_root_inode(ei);
rei->events_dir = dentry;
- rei->parent_inode = d_inode(dentry->d_sb->s_root);
ei->entries = entries;
ei->nr_entries = size;
--
2.43.0
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