xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ovl: do not try to reconnect a disconnected origin dentry

Browse Source 
On lookup of non directory, we try to decode the origin file handle
stored in upper inode. The origin file handle is supposed to be decoded
to a disconnected non-dir dentry, which is fine, because we only need
the lower inode of a copy up origin.

However, if the origin file handle somehow turns out to be a directory
we pay the expensive cost of reconnecting the directory dentry, only to
get a mismatch file type and drop the dentry.

Optimize this case by explicitly opting out of reconnecting the dentry.
Opting-out of reconnect is done by passing a NULL acceptable callback
to exportfs_decode_fh().

While the case described above is a strange corner case that does not
really need to be optimized, the API added for this optimization will
be used by a following patch to optimize a more common case of decoding
an overlayfs file handle.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein
2018-03-09 15:51:02 +02:00
committed by Miklos Szeredi
parent 5b2cccd32c
commit 8a22efa15b
4 changed files with 23 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
fs/overlayfs/export.c
View File

@@ -685,7 +685,7 @@ static struct dentry *ovl_upper_fh_to_d(struct super_block *sb,
if (!ofs->upper_mnt)
return ERR_PTR(-EACCES);
upper = ovl_decode_real_fh(fh, ofs->upper_mnt);
upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
if (IS_ERR_OR_NULL(upper))
return upper;
@@ -735,7 +735,7 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
}
/* Then lookup origin by fh */
err = ovl_check_origin_fh(ofs, fh, NULL, &stack);
err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack);
if (err) {
goto out_err;
} else if (index) {