[PATCH 1/2] proc: decouple proc from VFS with "struct proc_ops"

From: Alexey Dobriyan
Date: Wed Dec 25 2019 - 12:22:44 EST

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Currently core /proc code uses "struct file_operations" for custom
hooks, however, VFS doesn't directly call them. Every time VFS expands
file_operations hook set, /proc code bloats for no reason.

Introduce "struct proc_ops" which contains only those hooks which /proc
allows to call into (open, release, read, write, ioctl, mmap, poll).
It doesn't contain module pointer as well.

Save ~184 bytes per usage:

add/remove: 26/26 grow/shrink: 1/4 up/down: 1922/-6674 (-4752)
Function old new delta
sysvipc_proc_ops - 72 +72
...
config_gz_proc_ops - 72 +72
proc_get_inode 289 339 +50
proc_reg_get_unmapped_area 110 107 -3
close_pdeo 227 224 -3
proc_reg_open 289 284 -5
proc_create_data 60 53 -7
rt_cpu_seq_fops 256 - -256
...
default_affinity_proc_fops 256 - -256
Total: Before=5430095, After=5425343, chg -0.09%

Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
---

fs/proc/generic.c | 38 +++++++++++-------------
fs/proc/inode.c | 76 ++++++++++++++++++++++++------------------------
fs/proc/internal.h | 5 ++-
fs/proc/proc_net.c | 32 ++++++++++----------
fs/proc/proc_sysctl.c | 2 -
fs/proc/root.c | 2 -
include/linux/proc_fs.h | 23 ++++++++++++--
7 files changed, 98 insertions(+), 80 deletions(-)

--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -473,7 +473,7 @@ struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode,
ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
if (ent) {
ent->data = data;
- ent->proc_fops = &proc_dir_operations;
+ ent->proc_dir_ops = &proc_dir_operations;
ent->proc_iops = &proc_dir_inode_operations;
ent = proc_register(parent, ent);
}
@@ -503,7 +503,7 @@ struct proc_dir_entry *proc_create_mount_point(const char *name)
ent = __proc_create(&parent, name, mode, 2);
if (ent) {
ent->data = NULL;
- ent->proc_fops = NULL;
+ ent->proc_dir_ops = NULL;
ent->proc_iops = NULL;
ent = proc_register(parent, ent);
}
@@ -533,25 +533,23 @@ struct proc_dir_entry *proc_create_reg(const char *name, umode_t mode,

struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
struct proc_dir_entry *parent,
- const struct file_operations *proc_fops, void *data)
+ const struct proc_ops *proc_ops, void *data)
{
struct proc_dir_entry *p;

- BUG_ON(proc_fops == NULL);
-
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
- p->proc_fops = proc_fops;
+ p->proc_ops = proc_ops;
return proc_register(parent, p);
}
EXPORT_SYMBOL(proc_create_data);

struct proc_dir_entry *proc_create(const char *name, umode_t mode,
struct proc_dir_entry *parent,
- const struct file_operations *proc_fops)
+ const struct proc_ops *proc_ops)
{
- return proc_create_data(name, mode, parent, proc_fops, NULL);
+ return proc_create_data(name, mode, parent, proc_ops, NULL);
}
EXPORT_SYMBOL(proc_create);

@@ -573,11 +571,11 @@ static int proc_seq_release(struct inode *inode, struct file *file)
return seq_release(inode, file);
}

-static const struct file_operations proc_seq_fops = {
- .open = proc_seq_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = proc_seq_release,
+static const struct proc_ops proc_seq_ops = {
+ .proc_open = proc_seq_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_release = proc_seq_release,
};

struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
@@ -589,7 +587,7 @@ struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
- p->proc_fops = &proc_seq_fops;
+ p->proc_ops = &proc_seq_ops;
p->seq_ops = ops;
p->state_size = state_size;
return proc_register(parent, p);
@@ -603,11 +601,11 @@ static int proc_single_open(struct inode *inode, struct file *file)
return single_open(file, de->single_show, de->data);
}

-static const struct file_operations proc_single_fops = {
- .open = proc_single_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+static const struct proc_ops proc_single_ops = {
+ .proc_open = proc_single_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_release = single_release,
};

struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
@@ -619,7 +617,7 @@ struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
- p->proc_fops = &proc_single_fops;
+ p->proc_ops = &proc_single_ops;
p->single_show = show;
return proc_register(parent, p);
}
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -163,7 +163,7 @@ static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
pdeo->closing = true;
spin_unlock(&pde->pde_unload_lock);
file = pdeo->file;
- pde->proc_fops->release(file_inode(file), file);
+ pde->proc_ops->proc_release(file_inode(file), file);
spin_lock(&pde->pde_unload_lock);
/* After ->release. */
list_del(&pdeo->lh);
@@ -200,12 +200,12 @@ static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
struct proc_dir_entry *pde = PDE(file_inode(file));
loff_t rv = -EINVAL;
if (use_pde(pde)) {
- typeof_member(struct file_operations, llseek) llseek;
+ typeof_member(struct proc_ops, proc_lseek) lseek;

- llseek = pde->proc_fops->llseek;
- if (!llseek)
- llseek = default_llseek;
- rv = llseek(file, offset, whence);
+ lseek = pde->proc_ops->proc_lseek;
+ if (!lseek)
+ lseek = default_llseek;
+ rv = lseek(file, offset, whence);
unuse_pde(pde);
}
return rv;
@@ -216,9 +216,9 @@ static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count,
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;
if (use_pde(pde)) {
- typeof_member(struct file_operations, read) read;
+ typeof_member(struct proc_ops, proc_read) read;

- read = pde->proc_fops->read;
+ read = pde->proc_ops->proc_read;
if (read)
rv = read(file, buf, count, ppos);
unuse_pde(pde);
@@ -231,9 +231,9 @@ static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;
if (use_pde(pde)) {
- typeof_member(struct file_operations, write) write;
+ typeof_member(struct proc_ops, proc_write) write;

- write = pde->proc_fops->write;
+ write = pde->proc_ops->proc_write;
if (write)
rv = write(file, buf, count, ppos);
unuse_pde(pde);
@@ -246,9 +246,9 @@ static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
struct proc_dir_entry *pde = PDE(file_inode(file));
__poll_t rv = DEFAULT_POLLMASK;
if (use_pde(pde)) {
- typeof_member(struct file_operations, poll) poll;
+ typeof_member(struct proc_ops, proc_poll) poll;

- poll = pde->proc_fops->poll;
+ poll = pde->proc_ops->proc_poll;
if (poll)
rv = poll(file, pts);
unuse_pde(pde);
@@ -261,9 +261,9 @@ static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigne
struct proc_dir_entry *pde = PDE(file_inode(file));
long rv = -ENOTTY;
if (use_pde(pde)) {
- typeof_member(struct file_operations, unlocked_ioctl) ioctl;
+ typeof_member(struct proc_ops, proc_ioctl) ioctl;

- ioctl = pde->proc_fops->unlocked_ioctl;
+ ioctl = pde->proc_ops->proc_ioctl;
if (ioctl)
rv = ioctl(file, cmd, arg);
unuse_pde(pde);
@@ -277,9 +277,9 @@ static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned
struct proc_dir_entry *pde = PDE(file_inode(file));
long rv = -ENOTTY;
if (use_pde(pde)) {
- typeof_member(struct file_operations, compat_ioctl) compat_ioctl;
+ typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;

- compat_ioctl = pde->proc_fops->compat_ioctl;
+ compat_ioctl = pde->proc_ops->proc_compat_ioctl;
if (compat_ioctl)
rv = compat_ioctl(file, cmd, arg);
unuse_pde(pde);
@@ -293,9 +293,9 @@ static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
struct proc_dir_entry *pde = PDE(file_inode(file));
int rv = -EIO;
if (use_pde(pde)) {
- typeof_member(struct file_operations, mmap) mmap;
+ typeof_member(struct proc_ops, proc_mmap) mmap;

- mmap = pde->proc_fops->mmap;
+ mmap = pde->proc_ops->proc_mmap;
if (mmap)
rv = mmap(file, vma);
unuse_pde(pde);
@@ -312,9 +312,9 @@ proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
unsigned long rv = -EIO;

if (use_pde(pde)) {
- typeof_member(struct file_operations, get_unmapped_area) get_area;
+ typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;

- get_area = pde->proc_fops->get_unmapped_area;
+ get_area = pde->proc_ops->proc_get_unmapped_area;
#ifdef CONFIG_MMU
if (!get_area)
get_area = current->mm->get_unmapped_area;
@@ -333,8 +333,8 @@ static int proc_reg_open(struct inode *inode, struct file *file)
{
struct proc_dir_entry *pde = PDE(inode);
int rv = 0;
- typeof_member(struct file_operations, open) open;
- typeof_member(struct file_operations, release) release;
+ typeof_member(struct proc_ops, proc_open) open;
+ typeof_member(struct proc_ops, proc_release) release;
struct pde_opener *pdeo;

/*
@@ -351,7 +351,7 @@ static int proc_reg_open(struct inode *inode, struct file *file)
if (!use_pde(pde))
return -ENOENT;

- release = pde->proc_fops->release;
+ release = pde->proc_ops->proc_release;
if (release) {
pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
if (!pdeo) {
@@ -360,7 +360,7 @@ static int proc_reg_open(struct inode *inode, struct file *file)
}
}

- open = pde->proc_fops->open;
+ open = pde->proc_ops->proc_open;
if (open)
rv = open(inode, file);

@@ -468,21 +468,23 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
inode->i_size = de->size;
if (de->nlink)
set_nlink(inode, de->nlink);
- WARN_ON(!de->proc_iops);
- inode->i_op = de->proc_iops;
- if (de->proc_fops) {
- if (S_ISREG(inode->i_mode)) {
+
+ if (S_ISREG(inode->i_mode)) {
+ inode->i_op = de->proc_iops;
+ inode->i_fop = &proc_reg_file_ops;
#ifdef CONFIG_COMPAT
- if (!de->proc_fops->compat_ioctl)
- inode->i_fop =
- &proc_reg_file_ops_no_compat;
- else
-#endif
- inode->i_fop = &proc_reg_file_ops;
- } else {
- inode->i_fop = de->proc_fops;
+ if (!de->proc_ops->proc_compat_ioctl) {
+ inode->i_fop = &proc_reg_file_ops_no_compat;
}
- }
+#endif
+ } else if (S_ISDIR(inode->i_mode)) {
+ inode->i_op = de->proc_iops;
+ inode->i_fop = de->proc_dir_ops;
+ } else if (S_ISLNK(inode->i_mode)) {
+ inode->i_op = de->proc_iops;
+ inode->i_fop = NULL;
+ } else
+ BUG();
} else
pde_put(de);
return inode;
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -39,7 +39,10 @@ struct proc_dir_entry {
spinlock_t pde_unload_lock;
struct completion *pde_unload_completion;
const struct inode_operations *proc_iops;
- const struct file_operations *proc_fops;
+ union {
+ const struct proc_ops *proc_ops;
+ const struct file_operations *proc_dir_ops;
+ };
const struct dentry_operations *proc_dops;
union {
const struct seq_operations *seq_ops;
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -90,12 +90,12 @@ static int seq_release_net(struct inode *ino, struct file *f)
return 0;
}

-static const struct file_operations proc_net_seq_fops = {
- .open = seq_open_net,
- .read = seq_read,
- .write = proc_simple_write,
- .llseek = seq_lseek,
- .release = seq_release_net,
+static const struct proc_ops proc_net_seq_ops = {
+ .proc_open = seq_open_net,
+ .proc_read = seq_read,
+ .proc_write = proc_simple_write,
+ .proc_lseek = seq_lseek,
+ .proc_release = seq_release_net,
};

struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
@@ -108,7 +108,7 @@ struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
if (!p)
return NULL;
pde_force_lookup(p);
- p->proc_fops = &proc_net_seq_fops;
+ p->proc_ops = &proc_net_seq_ops;
p->seq_ops = ops;
p->state_size = state_size;
return proc_register(parent, p);
@@ -152,7 +152,7 @@ struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode
if (!p)
return NULL;
pde_force_lookup(p);
- p->proc_fops = &proc_net_seq_fops;
+ p->proc_ops = &proc_net_seq_ops;
p->seq_ops = ops;
p->state_size = state_size;
p->write = write;
@@ -183,12 +183,12 @@ static int single_release_net(struct inode *ino, struct file *f)
return single_release(ino, f);
}

-static const struct file_operations proc_net_single_fops = {
- .open = single_open_net,
- .read = seq_read,
- .write = proc_simple_write,
- .llseek = seq_lseek,
- .release = single_release_net,
+static const struct proc_ops proc_net_single_ops = {
+ .proc_open = single_open_net,
+ .proc_read = seq_read,
+ .proc_write = proc_simple_write,
+ .proc_lseek = seq_lseek,
+ .proc_release = single_release_net,
};

struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
@@ -201,7 +201,7 @@ struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
if (!p)
return NULL;
pde_force_lookup(p);
- p->proc_fops = &proc_net_single_fops;
+ p->proc_ops = &proc_net_single_ops;
p->single_show = show;
return proc_register(parent, p);
}
@@ -244,7 +244,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
if (!p)
return NULL;
pde_force_lookup(p);
- p->proc_fops = &proc_net_single_fops;
+ p->proc_ops = &proc_net_single_ops;
p->single_show = show;
p->write = write;
return proc_register(parent, p);
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1720,7 +1720,7 @@ int __init proc_sys_init(void)

proc_sys_root = proc_mkdir("sys", NULL);
proc_sys_root->proc_iops = &proc_sys_dir_operations;
- proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
+ proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;
proc_sys_root->nlink = 0;

return sysctl_init();
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -292,7 +292,7 @@ struct proc_dir_entry proc_root = {
.nlink = 2,
.refcnt = REFCOUNT_INIT(1),
.proc_iops = &proc_root_inode_operations,
- .proc_fops = &proc_root_operations,
+ .proc_dir_ops = &proc_root_operations,
.parent = &proc_root,
.subdir = RB_ROOT,
.name = "/proc",
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -12,6 +12,21 @@ struct proc_dir_entry;
struct seq_file;
struct seq_operations;

+struct proc_ops {
+ int (*proc_open)(struct inode *, struct file *);
+ ssize_t (*proc_read)(struct file *, char __user *, size_t, loff_t *);
+ ssize_t (*proc_write)(struct file *, const char __user *, size_t, loff_t *);
+ loff_t (*proc_lseek)(struct file *, loff_t, int);
+ int (*proc_release)(struct inode *, struct file *);
+ __poll_t (*proc_poll)(struct file *, struct poll_table_struct *);
+ long (*proc_ioctl)(struct file *, unsigned int, unsigned long);
+#ifdef CONFIG_COMPAT
+ long (*proc_compat_ioctl)(struct file *, unsigned int, unsigned long);
+#endif
+ int (*proc_mmap)(struct file *, struct vm_area_struct *);
+ unsigned long (*proc_get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
+};
+
#ifdef CONFIG_PROC_FS

typedef int (*proc_write_t)(struct file *, char *, size_t);
@@ -43,10 +58,10 @@ struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,

extern struct proc_dir_entry *proc_create_data(const char *, umode_t,
struct proc_dir_entry *,
- const struct file_operations *,
+ const struct proc_ops *,
void *);

-struct proc_dir_entry *proc_create(const char *name, umode_t mode, struct proc_dir_entry *parent, const struct file_operations *proc_fops);
+struct proc_dir_entry *proc_create(const char *name, umode_t mode, struct proc_dir_entry *parent, const struct proc_ops *proc_ops);
extern void proc_set_size(struct proc_dir_entry *, loff_t);
extern void proc_set_user(struct proc_dir_entry *, kuid_t, kgid_t);
extern void *PDE_DATA(const struct inode *);
@@ -108,8 +123,8 @@ static inline struct proc_dir_entry *proc_mkdir_mode(const char *name,
#define proc_create_seq(name, mode, parent, ops) ({NULL;})
#define proc_create_single(name, mode, parent, show) ({NULL;})
#define proc_create_single_data(name, mode, parent, show, data) ({NULL;})
-#define proc_create(name, mode, parent, proc_fops) ({NULL;})
-#define proc_create_data(name, mode, parent, proc_fops, data) ({NULL;})
+#define proc_create(name, mode, parent, proc_ops) ({NULL;})
+#define proc_create_data(name, mode, parent, proc_ops, data) ({NULL;})

static inline void proc_set_size(struct proc_dir_entry *de, loff_t size) {}
static inline void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid) {}

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