Kernel/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2025-01-01 10:45:49 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

eventfs: Stop using dcache_readdir() for getdents()

Browse Source 
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.

Link: https://lore.kernel.org/linux-trace-kernel/20240104015435.682218477@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ajay Kaher <akaher@vmware.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2024-01-03 20:52:49 -05:00
parent b0f7e2d739
commit 493ec81a8f
1 changed files with 64 additions and 130 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

194
fs/tracefs/event_inode.c
View File

@ -52,9 +52,7 @@ enum {
static struct dentry *eventfs_root_lookup(struct inode *dir, static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry, struct dentry *dentry,
unsigned int flags); unsigned int flags);
static int dcache_dir_open_wrapper(struct inode *inode, struct file *file); static int eventfs_iterate(struct file *file, struct dir_context *ctx);
static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx);
static int eventfs_release(struct inode *inode, struct file *file);
static void update_attr(struct eventfs_attr *attr, struct iattr *iattr) 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 = { static const struct file_operations eventfs_file_operations = {
.open = dcache_dir_open_wrapper,
.read = generic_read_dir, .read = generic_read_dir,
.iterate_shared = dcache_readdir_wrapper, .iterate_shared = eventfs_iterate,
.llseek = generic_file_llseek, .llseek = generic_file_llseek,
.release = eventfs_release,
}; };
/* Return the evenfs_inode of the "events" directory */ /* Return the evenfs_inode of the "events" directory */
@ -643,128 +639,87 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
return ret; return ret;
} }
struct dentry_list { /*
void *cursor; * Walk the children of a eventfs_inode to fill in getdents().
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) static int eventfs_iterate(struct file *file, struct dir_context *ctx)
{
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
*/
static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
{ {
const struct file_operations *fops; const struct file_operations *fops;
struct inode *f_inode = file_inode(file);
const struct eventfs_entry *entry; const struct eventfs_entry *entry;
struct eventfs_inode *ei_child; struct eventfs_inode *ei_child;
struct tracefs_inode *ti; struct tracefs_inode *ti;
struct eventfs_inode *ei; struct eventfs_inode *ei;
struct dentry_list *dlist; struct dentry *ei_dentry = NULL;
struct dentry **dentries = NULL; struct dentry *dentry;
struct dentry *parent = file_dentry(file); const char *name;
struct dentry *d;
struct inode *f_inode = file_inode(file);
const char *name = parent->d_name.name;
umode_t mode; umode_t mode;
void *data;
int cnt = 0;
int idx; int idx;
int ret; int ret = -EINVAL;
int i; int ino;
int r; int i, r, c;
if (!dir_emit_dots(file, ctx))
return 0;
ti = get_tracefs(f_inode); ti = get_tracefs(f_inode);
if (!(ti->flags & TRACEFS_EVENT_INODE)) if (!(ti->flags & TRACEFS_EVENT_INODE))
return -EINVAL; return -EINVAL;
if (WARN_ON_ONCE(file->private_data)) c = ctx->pos - 2;
return -EINVAL;
idx = srcu_read_lock(&eventfs_srcu); idx = srcu_read_lock(&eventfs_srcu);
mutex_lock(&eventfs_mutex); mutex_lock(&eventfs_mutex);
ei = READ_ONCE(ti->private); ei = READ_ONCE(ti->private);
if (ei && !ei->is_freed)
ei_dentry = READ_ONCE(ei->dentry);
mutex_unlock(&eventfs_mutex); mutex_unlock(&eventfs_mutex);
if (!ei) { if (!ei || !ei_dentry)
srcu_read_unlock(&eventfs_srcu, idx); goto out;
return -EINVAL;
}
ret = 0;
data = ei->data; /*
* Need to create the dentries and inodes to have a consistent
dlist = kmalloc(sizeof(*dlist), GFP_KERNEL); * inode number.
if (!dlist) { */
srcu_read_unlock(&eventfs_srcu, idx);
return -ENOMEM;
}
inode_lock(parent->d_inode);
list_for_each_entry_srcu(ei_child, &ei->children, list, list_for_each_entry_srcu(ei_child, &ei->children, list,
srcu_read_lock_held(&eventfs_srcu)) { srcu_read_lock_held(&eventfs_srcu)) {
d = create_dir_dentry(ei, ei_child, parent);
if (d) { if (c > 0) {
ret = add_dentries(&dentries, d, cnt); c--;
dput(d); continue;
if (ret < 0)
break;
cnt++;
} }
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++) { for (i = 0; i < ei->nr_entries; i++) {
void *cdata = data; void *cdata = ei->data;
if (c > 0) {
c--;
continue;
}
entry = &ei->entries[i]; entry = &ei->entries[i];
name = entry->name; name = entry->name;
mutex_lock(&eventfs_mutex); mutex_lock(&eventfs_mutex);
/* If ei->is_freed, then the event itself may be too */ /* If ei->is_freed, then the event itself may be too */
if (!ei->is_freed) if (!ei->is_freed)
@ -774,42 +729,21 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
mutex_unlock(&eventfs_mutex); mutex_unlock(&eventfs_mutex);
if (r <= 0) if (r <= 0)
continue; continue;
d = create_file_dentry(ei, i, parent, name, mode, cdata, fops);
if (d) { dentry = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops);
ret = add_dentries(&dentries, d, cnt); if (!dentry)
dput(d); goto out;
if (ret < 0) ino = dentry->d_inode->i_ino;
break; dput(dentry);
cnt++;
} if (!dir_emit(ctx, name, strlen(name), ino, DT_REG))
goto out;
ctx->pos++;
} }
inode_unlock(parent->d_inode); ret = 1;
out:
srcu_read_unlock(&eventfs_srcu, idx); 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;
}
/*
* 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;
file->private_data = dlist->cursor;
ret = dcache_readdir(file, ctx);
dlist->cursor = file->private_data;
file->private_data = dlist;
return ret; return ret;
} }