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| author | Christoph Hellwig <hch@lst.de> | 2023-08-02 17:41:26 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2023-08-11 13:15:03 +0200 |
| commit | 9c09a7cf6220a11dac0f4845b7e8925706cdc458 (patch) | |
| tree | 11a38fc43c68b4bd5989b86dee073b5f527e4c12 | |
| parent | fs: use the super_block as holder when mounting file systems (diff) | |
| download | linux-9c09a7cf6220a11dac0f4845b7e8925706cdc458.tar.xz linux-9c09a7cf6220a11dac0f4845b7e8925706cdc458.zip | |
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>
| -rw-r--r-- | fs/super.c | 30 |
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 = { |