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afs: Implement sillyrename for unlink and rename 

Implement sillyrename for AFS unlink and rename, using the NFS variant
implementation as a basis.

Note that the asynchronous file locking extender/releaser has to be
notified with a state change to stop it complaining if there's a race
between that and the actual file deletion.

A tracepoint, afs_silly_rename, is also added to note the silly rename and
the cleanup.  The afs_edit_dir tracepoint is given some extra reason
indicators and the afs_flock_ev tracepoint is given a silly-delete file
lock cancellation indicator.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2019-04-25 14:26:51 +01:00
parent 99987c5600
commit 79ddbfa500
8 changed files with 395 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/afs/Makefile
View File

@ -13,6 +13,7 @@ kafs-y := \
cmservice.o \
dir.o \
dir_edit.o \
dir_silly.o \
dynroot.o \
file.o \
flock.o \

116
fs/afs/dir.c
View File

@ -26,6 +26,7 @@ static int afs_dir_open(struct inode *inode, struct file *file);
static int afs_readdir(struct file *file, struct dir_context *ctx);
static int afs_d_revalidate(struct dentry *dentry, unsigned int flags);
static int afs_d_delete(const struct dentry *dentry);
static void afs_d_iput(struct dentry *dentry, struct inode *inode);
static int afs_lookup_one_filldir(struct dir_context *ctx, const char *name, int nlen,
loff_t fpos, u64 ino, unsigned dtype);
static int afs_lookup_filldir(struct dir_context *ctx, const char *name, int nlen,
@ -85,6 +86,7 @@ const struct dentry_operations afs_fs_dentry_operations = {
.d_delete = afs_d_delete,
.d_release = afs_d_release,
.d_automount = afs_d_automount,
.d_iput = afs_d_iput,
};
struct afs_lookup_one_cookie {
@ -1083,6 +1085,16 @@ zap:
return 1;
}
/*
* Clean up sillyrename files on dentry removal.
*/
static void afs_d_iput(struct dentry *dentry, struct inode *inode)
{
if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
afs_silly_iput(dentry, inode);
iput(inode);
}
/*
* handle dentry release
*/
@ -1225,6 +1237,12 @@ static int afs_rmdir(struct inode *dir, struct dentry *dentry)
goto error_key;
}
if (vnode) {
ret = down_write_killable(&vnode->rmdir_lock);
if (ret < 0)
goto error_key;
}
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, dvnode, key)) {
while (afs_select_fileserver(&fc)) {
@ -1243,6 +1261,8 @@ static int afs_rmdir(struct inode *dir, struct dentry *dentry)
}
}
if (vnode)
up_write(&vnode->rmdir_lock);
error_key:
key_put(key);
error:
@ -1259,9 +1279,9 @@ error:
* However, if we didn't have a callback promise outstanding, or it was
* outstanding on a different server, then it won't break it either...
*/
static int afs_dir_remove_link(struct dentry *dentry, struct key *key,
unsigned long d_version_before,
unsigned long d_version_after)
int afs_dir_remove_link(struct dentry *dentry, struct key *key,
unsigned long d_version_before,
unsigned long d_version_after)
{
bool dir_valid;
int ret = 0;
@ -1308,6 +1328,7 @@ static int afs_unlink(struct inode *dir, struct dentry *dentry)
struct afs_vnode *dvnode = AFS_FS_I(dir), *vnode = NULL;
struct key *key;
unsigned long d_version = (unsigned long)dentry->d_fsdata;
bool need_rehash = false;
u64 data_version = dvnode->status.data_version;
int ret;
@ -1331,6 +1352,21 @@ static int afs_unlink(struct inode *dir, struct dentry *dentry)
goto error_key;
}
spin_lock(&dentry->d_lock);
if (vnode && d_count(dentry) > 1) {
spin_unlock(&dentry->d_lock);
/* Start asynchronous writeout of the inode */
write_inode_now(d_inode(dentry), 0);
ret = afs_sillyrename(dvnode, vnode, dentry, key);
goto error_key;
}
if (!d_unhashed(dentry)) {
/* Prevent a race with RCU lookup. */
__d_drop(dentry);
need_rehash = true;
}
spin_unlock(&dentry->d_lock);
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, dvnode, key)) {
while (afs_select_fileserver(&fc)) {
@ -1362,6 +1398,9 @@ static int afs_unlink(struct inode *dir, struct dentry *dentry)
afs_edit_dir_for_unlink);
}
if (need_rehash && ret < 0 && ret != -ENOENT)
d_rehash(dentry);
error_key:
key_put(key);
error:
@ -1582,6 +1621,8 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
{
struct afs_fs_cursor fc;
struct afs_vnode *orig_dvnode, *new_dvnode, *vnode;
struct dentry *tmp = NULL, *rehash = NULL;
struct inode *new_inode;
struct key *key;
u64 orig_data_version, new_data_version;
bool new_negative = d_is_negative(new_dentry);
@ -1590,6 +1631,10 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
if (flags)
return -EINVAL;
/* Don't allow silly-rename files be moved around. */
if (old_dentry->d_flags & DCACHE_NFSFS_RENAMED)
return -EINVAL;
vnode = AFS_FS_I(d_inode(old_dentry));
orig_dvnode = AFS_FS_I(old_dir);
new_dvnode = AFS_FS_I(new_dir);
@ -1608,12 +1653,48 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
goto error;
}
/* For non-directories, check whether the target is busy and if so,
* make a copy of the dentry and then do a silly-rename. If the
* silly-rename succeeds, the copied dentry is hashed and becomes the
* new target.
*/
if (d_is_positive(new_dentry) && !d_is_dir(new_dentry)) {
/* To prevent any new references to the target during the
* rename, we unhash the dentry in advance.
*/
if (!d_unhashed(new_dentry)) {
d_drop(new_dentry);
rehash = new_dentry;
}
if (d_count(new_dentry) > 2) {
/* copy the target dentry's name */
ret = -ENOMEM;
tmp = d_alloc(new_dentry->d_parent,
&new_dentry->d_name);
if (!tmp)
goto error_rehash;
ret = afs_sillyrename(new_dvnode,
AFS_FS_I(d_inode(new_dentry)),
new_dentry, key);
if (ret)
goto error_rehash;
new_dentry = tmp;
rehash = NULL;
new_negative = true;
orig_data_version = orig_dvnode->status.data_version;
new_data_version = new_dvnode->status.data_version;
}
}
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, orig_dvnode, key)) {
if (orig_dvnode != new_dvnode) {
if (mutex_lock_interruptible_nested(&new_dvnode->io_lock, 1) < 0) {
afs_end_vnode_operation(&fc);
goto error_key;
goto error_rehash;
}
}
while (afs_select_fileserver(&fc)) {
@ -1630,25 +1711,42 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
mutex_unlock(&new_dvnode->io_lock);
ret = afs_end_vnode_operation(&fc);
if (ret < 0)
goto error_key;
goto error_rehash;
}
if (ret == 0) {
if (rehash)
d_rehash(rehash);
if (test_bit(AFS_VNODE_DIR_VALID, &orig_dvnode->flags))
afs_edit_dir_remove(orig_dvnode, &old_dentry->d_name,
afs_edit_dir_for_rename);
afs_edit_dir_for_rename_0);
if (!new_negative &&
test_bit(AFS_VNODE_DIR_VALID, &new_dvnode->flags))
afs_edit_dir_remove(new_dvnode, &new_dentry->d_name,
afs_edit_dir_for_rename);
afs_edit_dir_for_rename_1);
if (test_bit(AFS_VNODE_DIR_VALID, &new_dvnode->flags))
afs_edit_dir_add(new_dvnode, &new_dentry->d_name,
&vnode->fid, afs_edit_dir_for_rename);
&vnode->fid, afs_edit_dir_for_rename_2);
new_inode = d_inode(new_dentry);
if (new_inode) {
spin_lock(&new_inode->i_lock);
if (new_inode->i_nlink > 0)
drop_nlink(new_inode);
spin_unlock(&new_inode->i_lock);
}
d_move(old_dentry, new_dentry);
goto error_tmp;
}
error_key:
error_rehash:
if (rehash)
d_rehash(rehash);
error_tmp:
if (tmp)
dput(tmp);
key_put(key);
error:
_leave(" = %d", ret);

239
fs/afs/dir_silly.c Normal file
View File

@ -0,0 +1,239 @@
/* AFS silly rename handling
*
* Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* - Derived from NFS's sillyrename.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>
#include "internal.h"
/*
* Actually perform the silly rename step.
*/
static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
struct dentry *old, struct dentry *new,
struct key *key)
{
struct afs_fs_cursor fc;
u64 dir_data_version = dvnode->status.data_version;
int ret = -ERESTARTSYS;
_enter("%pd,%pd", old, new);
trace_afs_silly_rename(vnode, false);
if (afs_begin_vnode_operation(&fc, dvnode, key)) {
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(dvnode);
afs_fs_rename(&fc, old->d_name.name,
dvnode, new->d_name.name,
dir_data_version, dir_data_version);
}
afs_vnode_commit_status(&fc, dvnode, fc.cb_break);
ret = afs_end_vnode_operation(&fc);
}
if (ret == 0) {
spin_lock(&old->d_lock);
old->d_flags |= DCACHE_NFSFS_RENAMED;
spin_unlock(&old->d_lock);
if (dvnode->silly_key != key) {
key_put(dvnode->silly_key);
dvnode->silly_key = key_get(key);
}
if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
afs_edit_dir_remove(dvnode, &old->d_name,
afs_edit_dir_for_silly_0);
if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
afs_edit_dir_add(dvnode, &new->d_name,
&vnode->fid, afs_edit_dir_for_silly_1);
/* vfs_unlink and the like do not issue this when a file is
* sillyrenamed, so do it here.
*/
fsnotify_nameremove(old, 0);
}
_leave(" = %d", ret);
return ret;
}
/**
* afs_sillyrename - Perform a silly-rename of a dentry
*
* AFS is stateless and the server doesn't know when the client is holding a
* file open. To prevent application problems when a file is unlinked while
* it's still open, the client performs a "silly-rename". That is, it renames
* the file to a hidden file in the same directory, and only performs the
* unlink once the last reference to it is put.
*
* The final cleanup is done during dentry_iput.
*/
int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
struct dentry *dentry, struct key *key)
{
static unsigned int sillycounter;
struct dentry *sdentry = NULL;
unsigned char silly[16];
int ret = -EBUSY;
_enter("");
/* We don't allow a dentry to be silly-renamed twice. */
if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
return -EBUSY;
sdentry = NULL;
do {
int slen;
dput(sdentry);
sillycounter++;
/* Create a silly name. Note that the ".__afs" prefix is
* understood by the salvager and must not be changed.
*/
slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
sdentry = lookup_one_len(silly, dentry->d_parent, slen);
/* N.B. Better to return EBUSY here ... it could be dangerous
* to delete the file while it's in use.
*/
if (IS_ERR(sdentry))
goto out;
} while (!d_is_negative(sdentry));
ihold(&vnode->vfs_inode);
ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
switch (ret) {
case 0:
/* The rename succeeded. */
d_move(dentry, sdentry);
break;
case -ERESTARTSYS:
/* The result of the rename is unknown. Play it safe by forcing
* a new lookup.
*/
d_drop(dentry);
d_drop(sdentry);
}
iput(&vnode->vfs_inode);
dput(sdentry);
out:
_leave(" = %d", ret);
return ret;
}
/*
* Tell the server to remove a sillyrename file.
*/
static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
struct dentry *dentry, struct key *key)
{
struct afs_fs_cursor fc;
u64 dir_data_version = dvnode->status.data_version;
int ret = -ERESTARTSYS;
_enter("");
trace_afs_silly_rename(vnode, true);
if (afs_begin_vnode_operation(&fc, dvnode, key)) {
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(dvnode);
if (test_bit(AFS_SERVER_FL_IS_YFS, &fc.cbi->server->flags) &&
!test_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags)) {
yfs_fs_remove_file2(&fc, vnode, dentry->d_name.name,
dir_data_version);
if (fc.ac.error != -ECONNABORTED ||
fc.ac.abort_code != RXGEN_OPCODE)
continue;
set_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags);
}
afs_fs_remove(&fc, vnode, dentry->d_name.name, false,
dir_data_version);
}
afs_vnode_commit_status(&fc, dvnode, fc.cb_break);
ret = afs_end_vnode_operation(&fc);
if (ret == 0) {
drop_nlink(&vnode->vfs_inode);
if (vnode->vfs_inode.i_nlink == 0) {
set_bit(AFS_VNODE_DELETED, &vnode->flags);
clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
}
}
if (ret == 0 &&
test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
afs_edit_dir_remove(dvnode, &dentry->d_name,
afs_edit_dir_for_unlink);
}
_leave(" = %d", ret);
return ret;
}
/*
* Remove sillyrename file on iput.
*/
int afs_silly_iput(struct dentry *dentry, struct inode *inode)
{
struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
struct afs_vnode *vnode = AFS_FS_I(inode);
struct dentry *alias;
int ret;
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
_enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
down_read(&dvnode->rmdir_lock);
alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
if (IS_ERR(alias)) {
up_read(&dvnode->rmdir_lock);
return 0;
}
if (!d_in_lookup(alias)) {
/* We raced with lookup... See if we need to transfer the
* sillyrename information to the aliased dentry.
*/
ret = 0;
spin_lock(&alias->d_lock);
if (d_really_is_positive(alias) &&
!(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
alias->d_flags |= DCACHE_NFSFS_RENAMED;
ret = 1;
}
spin_unlock(&alias->d_lock);
up_read(&dvnode->rmdir_lock);
dput(alias);
return ret;
}
/* Stop lock-release from complaining. */
spin_lock(&vnode->lock);
vnode->lock_state = AFS_VNODE_LOCK_DELETED;
trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
spin_unlock(&vnode->lock);
afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
up_read(&dvnode->rmdir_lock);
d_lookup_done(alias);
dput(alias);
return 1;
}

2
fs/afs/flock.c
View File

@ -300,7 +300,7 @@ again:
/* attempt to release the server lock; if it fails, we just
* wait 5 minutes and it'll expire anyway */
ret = afs_release_lock(vnode, vnode->lock_key);
if (ret < 0) {
if (ret < 0 && vnode->lock_state != AFS_VNODE_LOCK_DELETED) {
trace_afs_flock_ev(vnode, NULL, afs_flock_release_fail,
ret);
printk(KERN_WARNING "AFS:"

2
fs/afs/inode.c
View File

@ -543,6 +543,8 @@ void afs_evict_inode(struct inode *inode)
#endif
afs_put_permits(rcu_access_pointer(vnode->permit_cache));
key_put(vnode->silly_key);
vnode->silly_key = NULL;
key_put(vnode->lock_key);
vnode->lock_key = NULL;
_leave("");

10
fs/afs/internal.h
View File

@ -621,6 +621,8 @@ struct afs_vnode {
struct afs_permits __rcu *permit_cache; /* cache of permits so far obtained */
struct mutex io_lock; /* Lock for serialising I/O on this mutex */
struct rw_semaphore validate_lock; /* lock for validating this vnode */
struct rw_semaphore rmdir_lock; /* Lock for rmdir vs sillyrename */
struct key *silly_key; /* Silly rename key */
spinlock_t wb_lock; /* lock for wb_keys */
spinlock_t lock; /* waitqueue/flags lock */
unsigned long flags;
@ -866,6 +868,7 @@ extern const struct address_space_operations afs_dir_aops;
extern const struct dentry_operations afs_fs_dentry_operations;
extern void afs_d_release(struct dentry *);
extern int afs_dir_remove_link(struct dentry *, struct key *, unsigned long, unsigned long);
/*
* dir_edit.c
@ -874,6 +877,13 @@ extern void afs_edit_dir_add(struct afs_vnode *, struct qstr *, struct afs_fid *
enum afs_edit_dir_reason);
extern void afs_edit_dir_remove(struct afs_vnode *, struct qstr *, enum afs_edit_dir_reason);
/*
* dir_silly.c
*/
extern int afs_sillyrename(struct afs_vnode *, struct afs_vnode *,
struct dentry *, struct key *);
extern int afs_silly_iput(struct dentry *, struct inode *);
/*
* dynroot.c
*/

4
fs/afs/super.c
View File

@ -45,7 +45,7 @@ struct file_system_type afs_fs_type = {
.init_fs_context = afs_init_fs_context,
.parameters = &afs_fs_parameters,
.kill_sb = afs_kill_super,
.fs_flags = 0,
.fs_flags = FS_RENAME_DOES_D_MOVE,
};
MODULE_ALIAS_FS("afs");
@ -656,6 +656,8 @@ static struct inode *afs_alloc_inode(struct super_block *sb)
vnode->cb_type = 0;
vnode->lock_state = AFS_VNODE_LOCK_NONE;
init_rwsem(&vnode->rmdir_lock);
_leave(" = %p", &vnode->vfs_inode);
return &vnode->vfs_inode;
}

34
include/trace/events/afs.h
View File

@ -108,8 +108,12 @@ enum afs_edit_dir_reason {
afs_edit_dir_for_create,
afs_edit_dir_for_link,
afs_edit_dir_for_mkdir,
afs_edit_dir_for_rename,
afs_edit_dir_for_rename_0,
afs_edit_dir_for_rename_1,
afs_edit_dir_for_rename_2,
afs_edit_dir_for_rmdir,
afs_edit_dir_for_silly_0,
afs_edit_dir_for_silly_1,
afs_edit_dir_for_symlink,
afs_edit_dir_for_unlink,
};
@ -161,6 +165,7 @@ enum afs_flock_event {
afs_flock_fail_perm,
afs_flock_no_lockers,
afs_flock_release_fail,
afs_flock_silly_delete,
afs_flock_timestamp,
afs_flock_try_to_lock,
afs_flock_vfs_lock,
@ -273,8 +278,12 @@ enum afs_flock_operation {
EM(afs_edit_dir_for_create, "Create") \
EM(afs_edit_dir_for_link, "Link ") \
EM(afs_edit_dir_for_mkdir, "MkDir ") \
EM(afs_edit_dir_for_rename, "Rename") \
EM(afs_edit_dir_for_rename_0, "Renam0") \
EM(afs_edit_dir_for_rename_1, "Renam1") \
EM(afs_edit_dir_for_rename_2, "Renam2") \
EM(afs_edit_dir_for_rmdir, "RmDir ") \
EM(afs_edit_dir_for_silly_0, "S_Ren0") \
EM(afs_edit_dir_for_silly_1, "S_Ren1") \
EM(afs_edit_dir_for_symlink, "Symlnk") \
E_(afs_edit_dir_for_unlink, "Unlink")
@ -337,6 +346,7 @@ enum afs_flock_operation {
EM(afs_flock_fail_perm, "ErrPerm ") \
EM(afs_flock_no_lockers, "NoLocker") \
EM(afs_flock_release_fail, "Rel_Fail") \
EM(afs_flock_silly_delete, "SillyDel") \
EM(afs_flock_timestamp, "Timestmp") \
EM(afs_flock_try_to_lock, "TryToLck") \
EM(afs_flock_vfs_lock, "VFSLock ") \
@ -964,6 +974,26 @@ TRACE_EVENT(afs_reload_dir,
__entry->fid.vid, __entry->fid.vnode, __entry->fid.unique)
);
TRACE_EVENT(afs_silly_rename,
TP_PROTO(struct afs_vnode *vnode, bool done),
TP_ARGS(vnode, done),
TP_STRUCT__entry(
__field_struct(struct afs_fid, fid )
__field(bool, done )
),
TP_fast_assign(
__entry->fid = vnode->fid;
__entry->done = done;
),
TP_printk("%llx:%llx:%x done=%u",
__entry->fid.vid, __entry->fid.vnode, __entry->fid.unique,
__entry->done)
);
#endif /* _TRACE_AFS_H */
/* This part must be outside protection */