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| author | Amir Goldstein <amir73il@gmail.com> | 2017-03-22 08:42:21 -0400 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2017-05-05 11:38:57 +0200 |
| commit | 7bcd74b98d7bac3e5149894caaf72de6989af7f0 (patch) | |
| tree | 0b7b0bb5dd7848ad6572b50d64ad81059e2b5fae /fs/overlayfs | |
| parent | 4a99f3c83dc493c8ea84693d78cd792839c8aa64 (diff) | |
| download | linux-7bcd74b98d7bac3e5149894caaf72de6989af7f0.tar.bz2 | |
ovl: check if all layers are on the same fs
Some features can only work when all layers are on the same fs. Test this
condition during mount time, so features can check them later.
Add helper ovl_same_sb() to return the common super block in case all
layers are on the same fs.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/overlayfs.h | 1 | ||||
| -rw-r--r-- | fs/overlayfs/ovl_entry.h | 2 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 8 | ||||
| -rw-r--r-- | fs/overlayfs/util.c | 7 |
4 files changed, 18 insertions, 0 deletions
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 741dc0b6931f..c851158324e2 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -151,6 +151,7 @@ int ovl_want_write(struct dentry *dentry); void ovl_drop_write(struct dentry *dentry); struct dentry *ovl_workdir(struct dentry *dentry); const struct cred *ovl_override_creds(struct super_block *sb); +struct super_block *ovl_same_sb(struct super_block *sb); struct ovl_entry *ovl_alloc_entry(unsigned int numlower); bool ovl_dentry_remote(struct dentry *dentry); bool ovl_dentry_weird(struct dentry *dentry); diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 59614faa14c3..b2023ddb8532 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -29,6 +29,8 @@ struct ovl_fs { const struct cred *creator_cred; bool tmpfile; wait_queue_head_t copyup_wq; + /* sb common to all layers */ + struct super_block *same_sb; }; /* private information held for every overlayfs dentry */ diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 6faefa54cb5e..9828b7de8999 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -914,11 +914,19 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ufs->lower_mnt[ufs->numlower] = mnt; ufs->numlower++; + + /* Check if all lower layers are on same sb */ + if (i == 0) + ufs->same_sb = mnt->mnt_sb; + else if (ufs->same_sb != mnt->mnt_sb) + ufs->same_sb = NULL; } /* If the upper fs is nonexistent, we mark overlayfs r/o too */ if (!ufs->upper_mnt) sb->s_flags |= MS_RDONLY; + else if (ufs->upper_mnt->mnt_sb != ufs->same_sb) + ufs->same_sb = NULL; if (remote) sb->s_d_op = &ovl_reval_dentry_operations; diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 35b8959db5ee..2bd4c264ccbe 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -41,6 +41,13 @@ const struct cred *ovl_override_creds(struct super_block *sb) return override_creds(ofs->creator_cred); } +struct super_block *ovl_same_sb(struct super_block *sb) +{ + struct ovl_fs *ofs = sb->s_fs_info; + + return ofs->same_sb; +} + struct ovl_entry *ovl_alloc_entry(unsigned int numlower) { size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); |