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| author | Amir Goldstein <amir73il@gmail.com> | 2018-03-09 15:51:02 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2018-04-12 12:04:49 +0200 |
| commit | 8a22efa15b46d524577cac79da63cebca8e8307f (patch) | |
| tree | d6c87569edb074ddd6edb3b88eb3105abefb3d6b /fs/overlayfs/export.c | |
| parent | 5b2cccd32c668de6bd1979545184cd7f0260f053 (diff) | |
| download | lwn-8a22efa15b46d524577cac79da63cebca8e8307f.tar.gz lwn-8a22efa15b46d524577cac79da63cebca8e8307f.zip | |
ovl: do not try to reconnect a disconnected origin dentry
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>
Diffstat (limited to 'fs/overlayfs/export.c')
| -rw-r--r-- | fs/overlayfs/export.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c index e688cf019460..15411350a7a1 100644 --- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -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) { |