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authorMickaël Salaün <mic@digikod.net>2023-06-12 22:14:25 +0300
committerMickaël Salaün <mic@digikod.net>2023-06-12 22:26:19 +0300
commit74ce793bcbde5cef0f82d6ccb3c47cb651295a9a (patch)
treeaf52b942aba6e0539e65ebfced7d46f8bb770cfd /fs/hostfs/hostfs_user.c
parent858fd168a95c5b9669aac8db6c14a9aeab446375 (diff)
downloadlinux-74ce793bcbde5cef0f82d6ccb3c47cb651295a9a.tar.xz
hostfs: Fix ephemeral inodes
hostfs creates a new inode for each opened or created file, which created useless inode allocations and forbade identifying a host file with a kernel inode. Fix this uncommon filesystem behavior by tying kernel inodes to host file's inode and device IDs. Even if the host filesystem inodes may be recycled, this cannot happen while a file referencing it is opened, which is the case with hostfs. It should be noted that hostfs inode IDs may not be unique for the same hostfs superblock because multiple host's (backed) superblocks may be used. Delete inodes when dropping them to force backed host's file descriptors closing. This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes Landlock fully supported by UML. This is very useful for testing changes. These changes also factor out and simplify some helpers thanks to the new hostfs_inode_update() and the hostfs_iget() revamp: read_name(), hostfs_create(), hostfs_lookup(), hostfs_mknod(), and hostfs_fill_sb_common(). A following commit with new Landlock tests check this new hostfs inode consistency. Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Acked-by: Richard Weinberger <richard@nod.at> Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
Diffstat (limited to 'fs/hostfs/hostfs_user.c')
-rw-r--r--fs/hostfs/hostfs_user.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c
index 5ecc4706172b..840619e39a1a 100644
--- a/fs/hostfs/hostfs_user.c
+++ b/fs/hostfs/hostfs_user.c
@@ -36,6 +36,7 @@ static void stat64_to_hostfs(const struct stat64 *buf, struct hostfs_stat *p)
p->blocks = buf->st_blocks;
p->maj = os_major(buf->st_rdev);
p->min = os_minor(buf->st_rdev);
+ p->dev = buf->st_dev;
}
int stat_file(const char *path, struct hostfs_stat *p, int fd)