Merge branch 'work.mount-base' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs mount API infrastructure updates from Al Viro:
 "Infrastructure bits of mount API conversions.

  The rest is more of per-filesystem updates and that will happen
  in separate pull requests"

* 'work.mount-base' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  mtd: Provide fs_context-aware mount_mtd() replacement
  vfs: Create fs_context-aware mount_bdev() replacement
  new helper: get_tree_keyed()
  vfs: set fs_context::user_ns for reconfigure
This commit is contained in:
Linus Torvalds 2019-09-18 13:15:58 -07:00
commit e170eb2771
10 changed files with 301 additions and 14 deletions

View File

@ -5,6 +5,7 @@
*/
extern struct mutex mtd_table_mutex;
extern struct backing_dev_info *mtd_bdi;
struct mtd_info *__mtd_next_device(int i);
int __must_check add_mtd_device(struct mtd_info *mtd);

View File

@ -15,6 +15,183 @@
#include <linux/slab.h>
#include <linux/major.h>
#include <linux/backing-dev.h>
#include <linux/fs_context.h>
#include "mtdcore.h"
/*
* compare superblocks to see if they're equivalent
* - they are if the underlying MTD device is the same
*/
static int mtd_test_super(struct super_block *sb, struct fs_context *fc)
{
struct mtd_info *mtd = fc->sget_key;
if (sb->s_mtd == fc->sget_key) {
pr_debug("MTDSB: Match on device %d (\"%s\")\n",
mtd->index, mtd->name);
return 1;
}
pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
return 0;
}
/*
* mark the superblock by the MTD device it is using
* - set the device number to be the correct MTD block device for pesuperstence
* of NFS exports
*/
static int mtd_set_super(struct super_block *sb, struct fs_context *fc)
{
sb->s_mtd = fc->sget_key;
sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
sb->s_bdi = bdi_get(mtd_bdi);
return 0;
}
/*
* get a superblock on an MTD-backed filesystem
*/
static int mtd_get_sb(struct fs_context *fc,
struct mtd_info *mtd,
int (*fill_super)(struct super_block *,
struct fs_context *))
{
struct super_block *sb;
int ret;
fc->sget_key = mtd;
sb = sget_fc(fc, mtd_test_super, mtd_set_super);
if (IS_ERR(sb))
return PTR_ERR(sb);
if (sb->s_root) {
/* new mountpoint for an already mounted superblock */
pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
mtd->index, mtd->name);
put_mtd_device(mtd);
} else {
/* fresh new superblock */
pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
mtd->index, mtd->name);
ret = fill_super(sb, fc);
if (ret < 0)
goto error_sb;
sb->s_flags |= SB_ACTIVE;
}
BUG_ON(fc->root);
fc->root = dget(sb->s_root);
return 0;
error_sb:
deactivate_locked_super(sb);
return ret;
}
/*
* get a superblock on an MTD-backed filesystem by MTD device number
*/
static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
int (*fill_super)(struct super_block *,
struct fs_context *))
{
struct mtd_info *mtd;
mtd = get_mtd_device(NULL, mtdnr);
if (IS_ERR(mtd)) {
errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
return PTR_ERR(mtd);
}
return mtd_get_sb(fc, mtd, fill_super);
}
/**
* get_tree_mtd - Get a superblock based on a single MTD device
* @fc: The filesystem context holding the parameters
* @fill_super: Helper to initialise a new superblock
*/
int get_tree_mtd(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc))
{
#ifdef CONFIG_BLOCK
struct block_device *bdev;
int ret, major;
#endif
int mtdnr;
if (!fc->source)
return invalf(fc, "No source specified");
pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
/* the preferred way of mounting in future; especially when
* CONFIG_BLOCK=n - we specify the underlying MTD device by number or
* by name, so that we don't require block device support to be present
* in the kernel.
*/
if (fc->source[0] == 'm' &&
fc->source[1] == 't' &&
fc->source[2] == 'd') {
if (fc->source[3] == ':') {
struct mtd_info *mtd;
/* mount by MTD device name */
pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
fc->source + 4);
mtd = get_mtd_device_nm(fc->source + 4);
if (!IS_ERR(mtd))
return mtd_get_sb(fc, mtd, fill_super);
errorf(fc, "MTD: MTD device with name \"%s\" not found",
fc->source + 4);
} else if (isdigit(fc->source[3])) {
/* mount by MTD device number name */
char *endptr;
mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
if (!*endptr) {
/* It was a valid number */
pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
}
}
}
#ifdef CONFIG_BLOCK
/* try the old way - the hack where we allowed users to mount
* /dev/mtdblock$(n) but didn't actually _use_ the blockdev
*/
bdev = lookup_bdev(fc->source);
if (IS_ERR(bdev)) {
ret = PTR_ERR(bdev);
errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
return ret;
}
pr_debug("MTDSB: lookup_bdev() returned 0\n");
major = MAJOR(bdev->bd_dev);
mtdnr = MINOR(bdev->bd_dev);
bdput(bdev);
if (major == MTD_BLOCK_MAJOR)
return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
#endif /* CONFIG_BLOCK */
if (!(fc->sb_flags & SB_SILENT))
errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
fc->source);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(get_tree_mtd);
/*
* compare superblocks to see if they're equivalent
@ -35,8 +212,6 @@ static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
return 0;
}
extern struct backing_dev_info *mtd_bdi;
/*
* mark the superblock by the MTD device it is using
* - set the device number to be the correct MTD block device for pesuperstence

View File

@ -279,10 +279,8 @@ static struct fs_context *alloc_fs_context(struct file_system_type *fs_type,
fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
break;
case FS_CONTEXT_FOR_RECONFIGURE:
/* We don't pin any namespaces as the superblock's
* subscriptions cannot be changed at this point.
*/
atomic_inc(&reference->d_sb->s_active);
fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
fc->root = dget(reference);
break;
}

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@ -1385,8 +1385,7 @@ static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc)
static int nfsd_fs_get_tree(struct fs_context *fc)
{
fc->s_fs_info = get_net(fc->net_ns);
return vfs_get_super(fc, vfs_get_keyed_super, nfsd_fill_super);
return get_tree_keyed(fc, nfsd_fill_super, get_net(fc->net_ns));
}
static void nfsd_fs_free_fc(struct fs_context *fc)

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@ -157,8 +157,7 @@ static int proc_get_tree(struct fs_context *fc)
{
struct proc_fs_context *ctx = fc->fs_private;
fc->s_fs_info = ctx->pid_ns;
return vfs_get_super(fc, vfs_get_keyed_super, proc_fill_super);
return get_tree_keyed(fc, proc_fill_super, ctx->pid_ns);
}
static void proc_fs_context_free(struct fs_context *fc)

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@ -1211,7 +1211,18 @@ int get_tree_single(struct fs_context *fc,
}
EXPORT_SYMBOL(get_tree_single);
int get_tree_keyed(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc),
void *key)
{
fc->s_fs_info = key;
return vfs_get_super(fc, vfs_get_keyed_super, fill_super);
}
EXPORT_SYMBOL(get_tree_keyed);
#ifdef CONFIG_BLOCK
static int set_bdev_super(struct super_block *s, void *data)
{
s->s_bdev = data;
@ -1221,6 +1232,99 @@ static int set_bdev_super(struct super_block *s, void *data)
return 0;
}
static int set_bdev_super_fc(struct super_block *s, struct fs_context *fc)
{
return set_bdev_super(s, fc->sget_key);
}
static int test_bdev_super_fc(struct super_block *s, struct fs_context *fc)
{
return s->s_bdev == fc->sget_key;
}
/**
* get_tree_bdev - Get a superblock based on a single block device
* @fc: The filesystem context holding the parameters
* @fill_super: Helper to initialise a new superblock
*/
int get_tree_bdev(struct fs_context *fc,
int (*fill_super)(struct super_block *,
struct fs_context *))
{
struct block_device *bdev;
struct super_block *s;
fmode_t mode = FMODE_READ | FMODE_EXCL;
int error = 0;
if (!(fc->sb_flags & SB_RDONLY))
mode |= FMODE_WRITE;
if (!fc->source)
return invalf(fc, "No source specified");
bdev = blkdev_get_by_path(fc->source, mode, fc->fs_type);
if (IS_ERR(bdev)) {
errorf(fc, "%s: Can't open blockdev", fc->source);
return PTR_ERR(bdev);
}
/* Once the superblock is inserted into the list by sget_fc(), s_umount
* will protect the lockfs code from trying to start a snapshot while
* we are mounting
*/
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (bdev->bd_fsfreeze_count > 0) {
mutex_unlock(&bdev->bd_fsfreeze_mutex);
warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev);
return -EBUSY;
}
fc->sb_flags |= SB_NOSEC;
fc->sget_key = bdev;
s = sget_fc(fc, test_bdev_super_fc, set_bdev_super_fc);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
if (IS_ERR(s))
return PTR_ERR(s);
if (s->s_root) {
/* Don't summarily change the RO/RW state. */
if ((fc->sb_flags ^ s->s_flags) & SB_RDONLY) {
warnf(fc, "%pg: Can't mount, would change RO state", bdev);
deactivate_locked_super(s);
blkdev_put(bdev, mode);
return -EBUSY;
}
/*
* s_umount nests inside bd_mutex during
* __invalidate_device(). blkdev_put() acquires
* bd_mutex and can't be called under s_umount. Drop
* s_umount temporarily. This is safe as we're
* holding an active reference.
*/
up_write(&s->s_umount);
blkdev_put(bdev, mode);
down_write(&s->s_umount);
} else {
s->s_mode = mode;
snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
sb_set_blocksize(s, block_size(bdev));
error = fill_super(s, fc);
if (error) {
deactivate_locked_super(s);
return error;
}
s->s_flags |= SB_ACTIVE;
bdev->bd_super = s;
}
BUG_ON(fc->root);
fc->root = dget(s->s_root);
return 0;
}
EXPORT_SYMBOL(get_tree_bdev);
static int test_bdev_super(struct super_block *s, void *data)
{
return (void *)s->s_bdev == data;

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@ -88,6 +88,7 @@ struct fs_context {
struct mutex uapi_mutex; /* Userspace access mutex */
struct file_system_type *fs_type;
void *fs_private; /* The filesystem's context */
void *sget_key;
struct dentry *root; /* The root and superblock */
struct user_namespace *user_ns; /* The user namespace for this mount */
struct net *net_ns; /* The network namespace for this mount */
@ -136,7 +137,7 @@ extern int vfs_get_tree(struct fs_context *fc);
extern void put_fs_context(struct fs_context *fc);
/*
* sget() wrapper to be called from the ->get_tree() op.
* sget() wrappers to be called from the ->get_tree() op.
*/
enum vfs_get_super_keying {
vfs_get_single_super, /* Only one such superblock may exist */
@ -147,12 +148,21 @@ extern int vfs_get_super(struct fs_context *fc,
enum vfs_get_super_keying keying,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc));
extern int get_tree_nodev(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc));
extern int get_tree_single(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc));
extern int get_tree_keyed(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc),
void *key);
extern int get_tree_bdev(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc));
extern const struct file_operations fscontext_fops;

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@ -14,6 +14,9 @@
#include <linux/fs.h>
#include <linux/mount.h>
extern int get_tree_mtd(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc));
extern struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
const char *dev_name, void *data,
int (*fill_super)(struct super_block *, void *, int));

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@ -364,8 +364,7 @@ static int mqueue_get_tree(struct fs_context *fc)
{
struct mqueue_fs_context *ctx = fc->fs_private;
fc->s_fs_info = ctx->ipc_ns;
return vfs_get_super(fc, vfs_get_keyed_super, mqueue_fill_super);
return get_tree_keyed(fc, mqueue_fill_super, ctx->ipc_ns);
}
static void mqueue_fs_context_free(struct fs_context *fc)

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@ -1416,8 +1416,7 @@ EXPORT_SYMBOL_GPL(gssd_running);
static int rpc_fs_get_tree(struct fs_context *fc)
{
fc->s_fs_info = get_net(fc->net_ns);
return vfs_get_super(fc, vfs_get_keyed_super, rpc_fill_super);
return get_tree_keyed(fc, rpc_fill_super, get_net(fc->net_ns));
}
static void rpc_fs_free_fc(struct fs_context *fc)