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ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry 

Now we have the notion of data dentry and metacopy dentry.
ovl_dentry_lower() will return uppermost lower dentry, but it could be
either data or metacopy dentry.  Now we support metacopy dentries in lower
layers so it is possible that lowerstack[0] is metacopy dentry while
lowerstack[1] is actual data dentry.

So add an helper which returns lowest most dentry which is supposed to be
data dentry.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Vivek Goyal 2018-05-11 11:49:30 -04:00 committed by Miklos Szeredi
parent 4f93b426ab
commit 647d253fcd
2 changed files with 14 additions and 0 deletions
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1
fs/overlayfs/overlayfs.h
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@ -221,6 +221,7 @@ void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry); struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry); struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
struct ovl_layer *ovl_layer_lower(struct dentry *dentry); struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry); struct dentry *ovl_dentry_real(struct dentry *dentry);
struct dentry *ovl_i_dentry_upper(struct inode *inode); struct dentry *ovl_i_dentry_upper(struct inode *inode);

13
fs/overlayfs/util.c
View File

@ -207,6 +207,19 @@ struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
return oe->numlower ? oe->lowerstack[0].layer : NULL; return oe->numlower ? oe->lowerstack[0].layer : NULL;
} }
/*
* ovl_dentry_lower() could return either a data dentry or metacopy dentry
* dependig on what is stored in lowerstack[0]. At times we need to find
* lower dentry which has data (and not metacopy dentry). This helper
* returns the lower data dentry.
*/
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
}
struct dentry *ovl_dentry_real(struct dentry *dentry) struct dentry *ovl_dentry_real(struct dentry *dentry)
{ {
return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry); return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);