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erofs: open via dedicated fs bdev helpers

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Route opens through fs_bdev_file_open_by_path() so each external device
is registered against the correct superblock, and convert the matching
releases.

Gao Xiang: I think typical immutable filesystems don't need .shutdown()
and .remove_bdev() for the following reasons:

  - blk_mark_disk_dead() sets GD_DEAD in advance of fs_bdev_mark_dead()
    so that the following bios will fail immediately; block_device
    references are still valid so it seems overkill to handle dead
    blockdevs in the deep filesystem I/O submission path.

  - Immutable filesystems like EROFS don't have write paths and journals,
    so they don't need to block writes (i.e., new dirty pages), metadata
    changes, and abort journals.

  - The comment above loop_change_fd() documents a valid read-only use
    case we need to support anyway, but it calls disk_force_media_change()
    which will call fs_bdev_mark_dead() later: we don't want loop_change_fd()
    shutdowns the active filesystems and return -EIO unconditionally.

Currently I think the default behavior (shrink_dcache_sb + evict_inodes)
in fs_bdev_mark_dead() is enough for immutable filesystems, tried to
document in the commit here for later reference.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://patch.msgid.link/20260616-work-super-bdev_holder_global-v2-14-7df6b864028e@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2026-06-16 16:08:30 +02:00
parent 7a7ef107b4
commit 69139a62a9
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 23 additions and 12 deletions
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35
fs/erofs/super.c
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@ -147,8 +147,8 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
if (!sbi->devs->flatdev) {
file = erofs_is_fileio_mode(sbi) ?
filp_open(dif->path, O_RDONLY | O_LARGEFILE, 0) :
bdev_file_open_by_path(dif->path,
BLK_OPEN_READ, sb->s_type, NULL);
fs_bdev_file_open_by_path(dif->path,
BLK_OPEN_READ, sb->s_type, sb);
if (IS_ERR(file)) {
if (file == ERR_PTR(-ENOTBLK))
return -EINVAL;
@ -799,28 +799,34 @@ static int erofs_fc_reconfigure(struct fs_context *fc)
static int erofs_release_device_info(int id, void *ptr, void *data)
{
struct super_block *sb = data;
struct erofs_device_info *dif = ptr;
fs_put_dax(dif->dax_dev, NULL);
if (dif->file)
fput(dif->file);
if (dif->file) {
if (S_ISBLK(file_inode(dif->file)->i_mode))
fs_bdev_file_release(dif->file, sb);
else
fput(dif->file);
}
kfree(dif->path);
kfree(dif);
return 0;
}
static void erofs_free_dev_context(struct erofs_dev_context *devs)
static void erofs_free_dev_context(struct erofs_dev_context *devs,
struct super_block *sb)
{
if (!devs)
return;
idr_for_each(&devs->tree, &erofs_release_device_info, NULL);
idr_for_each(&devs->tree, &erofs_release_device_info, sb);
idr_destroy(&devs->tree);
kfree(devs);
}
static void erofs_sb_free(struct erofs_sb_info *sbi)
static void erofs_sb_free(struct erofs_sb_info *sbi, struct super_block *sb)
{
erofs_free_dev_context(sbi->devs);
erofs_free_dev_context(sbi->devs, sb);
kfree_sensitive(sbi->domain_id);
if (sbi->dif0.file)
fput(sbi->dif0.file);
@ -832,8 +838,13 @@ static void erofs_fc_free(struct fs_context *fc)
{
struct erofs_sb_info *sbi = fc->s_fs_info;
if (sbi) /* free here if an error occurs before transferring to sb */
erofs_sb_free(sbi);
/*
* Freed here only if an error occurs before the sb is set up; at that
* point no block-backed device has been claimed (that happens in
* fill_super), so the NULL sb never reaches fs_bdev_file_release().
*/
if (sbi)
erofs_sb_free(sbi, NULL);
}
static const struct fs_context_operations erofs_context_ops = {
@ -887,7 +898,7 @@ static void erofs_kill_sb(struct super_block *sb)
kill_block_super(sb);
erofs_drop_internal_inodes(sbi);
fs_put_dax(sbi->dif0.dax_dev, NULL);
erofs_sb_free(sbi);
erofs_sb_free(sbi, sb);
sb->s_fs_info = NULL;
}
@ -899,7 +910,7 @@ static void erofs_put_super(struct super_block *sb)
erofs_shrinker_unregister(sb);
erofs_xattr_prefixes_cleanup(sb);
erofs_drop_internal_inodes(sbi);
erofs_free_dev_context(sbi->devs);
erofs_free_dev_context(sbi->devs, sb);
sbi->devs = NULL;
}