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authorDavid Howells <dhowells@redhat.com>2019-03-27 14:15:16 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2019-09-05 14:34:22 -0400
commitfe62c3a4e17ddfe672710425ab6eba2ba7203526 (patch)
tree4b8bfb4bbfbeb53c75b14f4522233ed3216749aa /fs/super.c
parent533770cc0ae84890624dc129609f3d75855c8982 (diff)
vfs: Create fs_context-aware mount_bdev() replacement
Create a function, get_tree_bdev(), that is fs_context-aware and a ->get_tree() counterpart of mount_bdev(). It caches the block device pointer in the fs_context struct so that this information can be passed into sget_fc()'s test and set functions. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jens Axboe <axboe@kernel.dk> cc: linux-block@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c94
1 files changed, 94 insertions, 0 deletions
diff --git a/fs/super.c b/fs/super.c
index 0220def9baba..da223b4cfbca 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1222,6 +1222,7 @@ int get_tree_keyed(struct fs_context *fc,
EXPORT_SYMBOL(get_tree_keyed);
#ifdef CONFIG_BLOCK
+
static int set_bdev_super(struct super_block *s, void *data)
{
s->s_bdev = data;
@@ -1231,6 +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;