This is needed for choosing between concurrent copyup
using O_TMPFILE and legacy copyup using workdir+rename.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/overlayfs.h | 9 +++++++++
fs/overlayfs/ovl_entry.h | 1 +
fs/overlayfs/super.c | 10 ++++++++++
3 files changed, 20 insertions(+)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 8af450b..d5984c4 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -127,6 +127,15 @@ static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
return err;
}
+static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
+{
+ struct dentry *ret = vfs_tmpfile(dentry->d_inode, dentry, mode, 0);
+ int err = IS_ERR(ret) ? PTR_ERR(ret) : 0;
+
+ pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
+ return ret;
+}
+
static inline struct inode *ovl_inode_real(struct inode *inode, bool *is_upper)
{
unsigned long x = (unsigned long) READ_ONCE(inode->i_private);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index d14bca1..65f24000 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -27,6 +27,7 @@ struct ovl_fs {
struct ovl_config config;
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
+ bool tmpfile;
};
/* private information held for every overlayfs dentry */
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 20f48ab..ff05065 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -825,6 +825,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
* creation of workdir in previous step.
*/
if (ufs->workdir) {
+ struct dentry *temp;
+
err = ovl_check_d_type_supported(&workpath);
if (err < 0)
goto out_put_workdir;
@@ -836,6 +838,14 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
*/
if (!err)
pr_warn("overlayfs: upper fs needs to support d_type.\n");
+
+ /* Check if upper/work fs supports O_TMPFILE */
+ temp = ovl_do_tmpfile(ufs->workdir, S_IFREG | 0);
+ ufs->tmpfile = !IS_ERR(temp);
+ if (ufs->tmpfile)
+ dput(temp);
+ else
+ pr_warn("overlayfs: upper fs does not support tmpfile.\n");
}
}
--
2.7.4
--
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