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authorChristoph Hellwig <hch@lst.de>2023-08-02 18:41:26 +0300
committerChristian Brauner <brauner@kernel.org>2023-08-11 14:15:03 +0300
commit9c09a7cf6220a11dac0f4845b7e8925706cdc458 (patch)
tree11a38fc43c68b4bd5989b86dee073b5f527e4c12 /fs/super.c
parent2ea6f68932f73a6a9d82160d3ad0a49a5a6bb183 (diff)
downloadlinux-9c09a7cf6220a11dac0f4845b7e8925706cdc458.tar.xz
fs: stop using get_super in fs_mark_dead
fs_mark_dead currently uses get_super to find the superblock for the block device that is going away. This means it is limited to the main device stored in sb->s_dev, leading to a lot of code duplication for file systems that can use multiple block devices. Now that the holder for all block devices used by file systems is set to the super_block, we can instead look at that holder and then check if the file system is born and active, so do that instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christian Brauner <brauner@kernel.org> Message-Id: <20230802154131.2221419-8-hch@lst.de> Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c30
1 files changed, 26 insertions, 4 deletions
diff --git a/fs/super.c b/fs/super.c
index 3c7e4633efeb..9cf7fc67727b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1209,17 +1209,39 @@ int get_tree_keyed(struct fs_context *fc,
EXPORT_SYMBOL(get_tree_keyed);
#ifdef CONFIG_BLOCK
+/*
+ * Lock a super block that the callers holds a reference to.
+ *
+ * The caller needs to ensure that the super_block isn't being freed while
+ * calling this function, e.g. by holding a lock over the call to this function
+ * and the place that clears the pointer to the superblock used by this function
+ * before freeing the superblock.
+ */
+static bool lock_active_super(struct super_block *sb)
+{
+ down_read(&sb->s_umount);
+ if (!sb->s_root ||
+ (sb->s_flags & (SB_ACTIVE | SB_BORN)) != (SB_ACTIVE | SB_BORN)) {
+ up_read(&sb->s_umount);
+ return false;
+ }
+ return true;
+}
+
static void fs_mark_dead(struct block_device *bdev)
{
- struct super_block *sb;
+ struct super_block *sb = bdev->bd_holder;
- sb = get_super(bdev);
- if (!sb)
+ /* bd_holder_lock ensures that the sb isn't freed */
+ lockdep_assert_held(&bdev->bd_holder_lock);
+
+ if (!lock_active_super(sb))
return;
if (sb->s_op->shutdown)
sb->s_op->shutdown(sb);
- drop_super(sb);
+
+ up_read(&sb->s_umount);
}
static const struct blk_holder_ops fs_holder_ops = {