From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
The eventfs creates dynamically allocated dentries and inodes. Using the
dcache_readdir() logic for its own directory lookups requires hiding the
cursor of the dcache logic and playing games to allow the dcache_readdir()
to still have access to the cursor while the eventfs saved what it created
and what it needs to release.
Instead, just have eventfs have its own iterate_shared callback function
that will fill in the dent entries. This simplifies the code quite a bit.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
fs/tracefs/event_inode.c | 194 +++++++++++++--------------------------
1 file changed, 64 insertions(+), 130 deletions(-)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index c360300fb866..41af56f44f0a 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -52,9 +52,7 @@ enum {
static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags);
-static int dcache_dir_open_wrapper(struct inode *inode, struct file *file);
-static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx);
-static int eventfs_release(struct inode *inode, struct file *file);
+static int eventfs_iterate(struct file *file, struct dir_context *ctx);
static void update_attr(struct eventfs_attr *attr, struct iattr *iattr)
{
@@ -148,11 +146,9 @@ static const struct inode_operations eventfs_file_inode_operations = {
};
static const struct file_operations eventfs_file_operations = {
- .open = dcache_dir_open_wrapper,
.read = generic_read_dir,
- .iterate_shared = dcache_readdir_wrapper,
+ .iterate_shared = eventfs_iterate,
.llseek = generic_file_llseek,
- .release = eventfs_release,
};
/* Return the evenfs_inode of the "events" directory */
@@ -643,128 +639,87 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
return ret;
}
-struct dentry_list {
- void *cursor;
- struct dentry **dentries;
-};
-
-/**
- * eventfs_release - called to release eventfs file/dir
- * @inode: inode to be released
- * @file: file to be released (not used)
- */
-static int eventfs_release(struct inode *inode, struct file *file)
-{
- struct tracefs_inode *ti;
- struct dentry_list *dlist = file->private_data;
- void *cursor;
- int i;
-
- ti = get_tracefs(inode);
- if (!(ti->flags & TRACEFS_EVENT_INODE))
- return -EINVAL;
-
- if (WARN_ON_ONCE(!dlist))
- return -EINVAL;
-
- for (i = 0; dlist->dentries && dlist->dentries[i]; i++) {
- dput(dlist->dentries[i]);
- }
-
- cursor = dlist->cursor;
- kfree(dlist->dentries);
- kfree(dlist);
- file->private_data = cursor;
- return dcache_dir_close(inode, file);
-}
-
-static int add_dentries(struct dentry ***dentries, struct dentry *d, int cnt)
-{
- struct dentry **tmp;
-
- tmp = krealloc(*dentries, sizeof(d) * (cnt + 2), GFP_NOFS);
- if (!tmp)
- return -1;
- tmp[cnt] = d;
- tmp[cnt + 1] = NULL;
- *dentries = tmp;
- return 0;
-}
-
-/**
- * dcache_dir_open_wrapper - eventfs open wrapper
- * @inode: not used
- * @file: dir to be opened (to create it's children)
- *
- * Used to dynamic create file/dir with-in @file, all the
- * file/dir will be created. If already created then references
- * will be increased
+/*
+ * Walk the children of a eventfs_inode to fill in getdents().
*/
-static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
+static int eventfs_iterate(struct file *file, struct dir_context *ctx)
{
const struct file_operations *fops;
+ struct inode *f_inode = file_inode(file);
const struct eventfs_entry *entry;
struct eventfs_inode *ei_child;
struct tracefs_inode *ti;
struct eventfs_inode *ei;
- struct dentry_list *dlist;
- struct dentry **dentries = NULL;
- struct dentry *parent = file_dentry(file);
- struct dentry *d;
- struct inode *f_inode = file_inode(file);
- const char *name = parent->d_name.name;
+ struct dentry *ei_dentry = NULL;
+ struct dentry *dentry;
+ const char *name;
umode_t mode;
- void *data;
- int cnt = 0;
int idx;
- int ret;
- int i;
- int r;
+ int ret = -EINVAL;
+ int ino;
+ int i, r, c;
+
+ if (!dir_emit_dots(file, ctx))
+ return 0;
ti = get_tracefs(f_inode);
if (!(ti->flags & TRACEFS_EVENT_INODE))
return -EINVAL;
- if (WARN_ON_ONCE(file->private_data))
- return -EINVAL;
+ c = ctx->pos - 2;
idx = srcu_read_lock(&eventfs_srcu);
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) {
- srcu_read_unlock(&eventfs_srcu, idx);
- return -EINVAL;
- }
-
-
- data = ei->data;
+ if (!ei || !ei_dentry)
+ goto out;
- dlist = kmalloc(sizeof(*dlist), GFP_KERNEL);
- if (!dlist) {
- srcu_read_unlock(&eventfs_srcu, idx);
- return -ENOMEM;
- }
+ ret = 0;
- inode_lock(parent->d_inode);
+ /*
+ * Need to create the dentries and inodes to have a consistent
+ * inode number.
+ */
list_for_each_entry_srcu(ei_child, &ei->children, list,
srcu_read_lock_held(&eventfs_srcu)) {
- d = create_dir_dentry(ei, ei_child, parent);
- if (d) {
- ret = add_dentries(&dentries, d, cnt);
- dput(d);
- if (ret < 0)
- break;
- cnt++;
+
+ if (c > 0) {
+ c--;
+ continue;
}
+
+ if (ei_child->is_freed)
+ continue;
+
+ name = ei_child->name;
+
+ dentry = create_dir_dentry(ei, ei_child, ei_dentry);
+ if (!dentry)
+ goto out;
+ ino = dentry->d_inode->i_ino;
+ dput(dentry);
+
+ if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR))
+ goto out;
+ ctx->pos++;
}
for (i = 0; i < ei->nr_entries; i++) {
- void *cdata = data;
+ void *cdata = ei->data;
+
+ if (c > 0) {
+ c--;
+ continue;
+ }
+
entry = &ei->entries[i];
name = entry->name;
+
mutex_lock(&eventfs_mutex);
/* If ei->is_freed, then the event itself may be too */
if (!ei->is_freed)
@@ -774,42 +729,21 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
mutex_unlock(&eventfs_mutex);
if (r <= 0)
continue;
- d = create_file_dentry(ei, i, parent, name, mode, cdata, fops);
- if (d) {
- ret = add_dentries(&dentries, d, cnt);
- dput(d);
- if (ret < 0)
- break;
- cnt++;
- }
- }
- inode_unlock(parent->d_inode);
- srcu_read_unlock(&eventfs_srcu, idx);
- ret = dcache_dir_open(inode, file);
- /*
- * dcache_dir_open() sets file->private_data to a dentry cursor.
- * Need to save that but also save all the dentries that were
- * opened by this function.
- */
- dlist->cursor = file->private_data;
- dlist->dentries = dentries;
- file->private_data = dlist;
- return ret;
-}
+ dentry = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops);
+ if (!dentry)
+ goto out;
+ ino = dentry->d_inode->i_ino;
+ dput(dentry);
-/*
- * This just sets the file->private_data back to the cursor and back.
- */
-static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx)
-{
- struct dentry_list *dlist = file->private_data;
- int ret;
+ if (!dir_emit(ctx, name, strlen(name), ino, DT_REG))
+ goto out;
+ ctx->pos++;
+ }
+ ret = 1;
+ out:
+ srcu_read_unlock(&eventfs_srcu, idx);
- file->private_data = dlist->cursor;
- ret = dcache_readdir(file, ctx);
- dlist->cursor = file->private_data;
- file->private_data = dlist;
return ret;
}
--
2.42.0
