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forked fromtorvalds/linux

Commitfff377d

Browse files
author
Jon Ayers
committed
whiteout patch
1 parentf36b753 commitfff377d

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6 files changed

+161
-10
lines changed

6 files changed

+161
-10
lines changed

‎fs/overlayfs/dir.c‎

Lines changed: 144 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -24,6 +24,12 @@ module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
2424
MODULE_PARM_DESC(ovl_redirect_max,
2525
"Maximum length of absolute redirect xattr value");
2626

27+
staticunsignedintovl_singleton_wt_link_max=255;
28+
module_param_named(singleton_whiteout_link_max,
29+
ovl_singleton_wt_link_max,uint,0644);
30+
MODULE_PARM_DESC(ovl_singleton_wt_link_max,
31+
"Maximum hardlinks of a whiteout singleton");
32+
2733
intovl_cleanup(structinode*wdir,structdentry*wdentry)
2834
{
2935
interr;
@@ -62,18 +68,149 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir)
6268
returntemp;
6369
}
6470

71+
#defineOVL_SINGLETON_WHITEOUT_NAME "whiteout"
72+
73+
/* caller holds write lock (i_rwsem) of dir */
74+
staticintovl_make_singleton_whiteout_locked(structovl_fs*ofs,
75+
structdentry*dir,constchar*name)
76+
{
77+
interr=0;
78+
structinode*inode=d_inode(dir);
79+
structdentry*whiteout;
80+
81+
whiteout=lookup_one_len(name,dir,strlen(name));
82+
if (IS_ERR(whiteout))
83+
returnPTR_ERR(whiteout);
84+
85+
if (ovl_is_whiteout(whiteout)) {
86+
ofs->whiteout=whiteout;
87+
}elseif (!whiteout->d_inode) {
88+
err=ovl_do_whiteout(inode,whiteout);
89+
if (!err)
90+
ofs->whiteout=whiteout;
91+
else
92+
dput(whiteout);
93+
}else {
94+
/*
95+
* fallback to creating new whiteout file if
96+
* a non-whiteout file already exists
97+
*/
98+
dput(whiteout);
99+
}
100+
101+
returnerr;
102+
}
103+
104+
/*
105+
* create a new whiteout file under workdir if it doesn't exist.
106+
* If a non-whiteout file already exists, no error will be reported
107+
* and the needed whiteout file will be newly created instead of
108+
* being linked to a singleton whiteout.
109+
*/
110+
intovl_make_singleton_whiteout(structovl_fs*ofs)
111+
{
112+
interr;
113+
structinode*dir;
114+
115+
/* disable singleton whiteout */
116+
if (ovl_singleton_wt_link_max <=1)
117+
return0;
118+
119+
dir=d_inode(ofs->workdir);
120+
inode_lock_nested(dir,I_MUTEX_PARENT);
121+
122+
err=ovl_make_singleton_whiteout_locked(ofs,ofs->workdir,
123+
OVL_SINGLETON_WHITEOUT_NAME);
124+
125+
inode_unlock(dir);
126+
127+
returnerr;
128+
}
129+
130+
/*
131+
* caller holds i_mutex of workdir to ensure the operations
132+
* on the singletion whiteout are serialized.
133+
*/
134+
staticintovl_link_to_singleton_whiteout(structovl_fs*ofs,
135+
structdentry*whiteout,bool*create_instead)
136+
{
137+
interr;
138+
structinode*wdir=d_inode(ofs->workdir);
139+
structdentry*singleton;
140+
boolretried= false;
141+
142+
*create_instead= false;
143+
retry:
144+
singleton=ofs->whiteout;
145+
/* Create a new singletion whiteout when the limit is exceeded */
146+
if (1<ovl_singleton_wt_link_max&&
147+
singleton->d_inode->i_nlink >=ovl_singleton_wt_link_max)
148+
err=-EMLINK;
149+
else
150+
err=ovl_do_link(singleton,wdir,whiteout, false);
151+
152+
if (!err) {
153+
gotoout;
154+
}elseif (err==-EMLINK&& !retried) {
155+
/*
156+
* The singleton already has the maximum number of links to it,
157+
* so remove the old singleton and create a new one
158+
*/
159+
ofs->whiteout=NULL;
160+
err=ovl_do_unlink(wdir,singleton);
161+
if (err) {
162+
dput(singleton);
163+
gotoout;
164+
}
165+
166+
dput(singleton);
167+
err=ovl_make_singleton_whiteout_locked(ofs,ofs->workdir,
168+
OVL_SINGLETON_WHITEOUT_NAME);
169+
if (err)
170+
gotoout;
171+
172+
retried= true;
173+
if (ofs->whiteout)
174+
gotoretry;
175+
else
176+
gotoout_fallback;
177+
}elseif (err==-EXDEV) {
178+
/*
179+
* upper fs may have a project id different than singleton,
180+
* so fall back to create whiteout directly
181+
*/
182+
gotoout_fallback;
183+
}else {
184+
gotoout;
185+
}
186+
187+
out_fallback:
188+
*create_instead= true;
189+
out:
190+
returnerr;
191+
}
192+
65193
/* caller holds i_mutex on workdir */
66-
staticstructdentry*ovl_whiteout(structdentry*workdir)
194+
staticstructdentry*ovl_whiteout(structovl_fs*ofs,structdentry*workdir)
67195
{
68196
interr;
69197
structdentry*whiteout;
70198
structinode*wdir=workdir->d_inode;
199+
boolcreate_instead;
71200

72201
whiteout=ovl_lookup_temp(workdir);
73202
if (IS_ERR(whiteout))
74203
returnwhiteout;
75204

76-
err=ovl_do_whiteout(wdir,whiteout);
205+
if (workdir==ofs->workdir&&ofs->whiteout)
206+
err=ovl_link_to_singleton_whiteout(ofs,whiteout,
207+
&create_instead);
208+
else
209+
create_instead= true;
210+
211+
if (create_instead)
212+
err=ovl_do_whiteout(wdir,whiteout);
213+
77214
if (err) {
78215
dput(whiteout);
79216
whiteout=ERR_PTR(err);
@@ -83,15 +220,15 @@ static struct dentry *ovl_whiteout(struct dentry *workdir)
83220
}
84221

85222
/* Caller must hold i_mutex on both workdir and dir */
86-
intovl_cleanup_and_whiteout(structdentry*workdir,structinode*dir,
87-
structdentry*dentry)
223+
intovl_cleanup_and_whiteout(structovl_fs*ofs,structdentry*workdir,
224+
structinode*dir,structdentry*dentry)
88225
{
89226
structinode*wdir=workdir->d_inode;
90227
structdentry*whiteout;
91228
interr;
92229
intflags=0;
93230

94-
whiteout=ovl_whiteout(workdir);
231+
whiteout=ovl_whiteout(ofs,workdir);
95232
err=PTR_ERR(whiteout);
96233
if (IS_ERR(whiteout))
97234
returnerr;
@@ -621,6 +758,7 @@ static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
621758
staticintovl_remove_and_whiteout(structdentry*dentry,
622759
structlist_head*list)
623760
{
761+
structovl_fs*ofs=dentry->d_sb->s_fs_info;
624762
structdentry*workdir=ovl_workdir(dentry);
625763
structdentry*upperdir=ovl_dentry_upper(dentry->d_parent);
626764
structdentry*upper;
@@ -654,7 +792,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
654792
gotoout_dput_upper;
655793
}
656794

657-
err=ovl_cleanup_and_whiteout(workdir,d_inode(upperdir),upper);
795+
err=ovl_cleanup_and_whiteout(ofs,workdir,d_inode(upperdir),upper);
658796
if (err)
659797
gotoout_d_drop;
660798

‎fs/overlayfs/overlayfs.h‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -344,8 +344,8 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
344344
/* dir.c */
345345
externconststructinode_operationsovl_dir_inode_operations;
346346
structdentry*ovl_lookup_temp(structdentry*workdir);
347-
intovl_cleanup_and_whiteout(structdentry*workdir,structinode*dir,
348-
structdentry*dentry);
347+
intovl_cleanup_and_whiteout(structovl_fs*ofs,structdentry*workdir,
348+
structinode*dir,structdentry*dentry);
349349
structcattr {
350350
dev_trdev;
351351
umode_tmode;
@@ -355,6 +355,7 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
355355
structcattr*attr,
356356
structdentry*hardlink,booldebug);
357357
intovl_cleanup(structinode*dir,structdentry*dentry);
358+
intovl_make_singleton_whiteout(structovl_fs*ofs);
358359

359360
/* copy_up.c */
360361
intovl_copy_up(structdentry*dentry);

‎fs/overlayfs/ovl_entry.h‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -43,6 +43,11 @@ struct ovl_fs {
4343
structdentry*workdir;
4444
/* index directory listing overlay inodes by origin file handle */
4545
structdentry*indexdir;
46+
/*
47+
* the singleton whiteout file under workdir: all newly created
48+
* whiteout files will be linked to it if possible
49+
*/
50+
structdentry*whiteout;
4651
longnamelen;
4752
/* pathnames of lower and upper dirs, for show_options */
4853
structovl_configconfig;

‎fs/overlayfs/readdir.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1084,7 +1084,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
10841084
* Whiteout orphan index to block future open by
10851085
* handle after overlay nlink dropped to zero.
10861086
*/
1087-
err=ovl_cleanup_and_whiteout(indexdir,dir,index);
1087+
err=ovl_cleanup_and_whiteout(ofs,indexdir,dir,index);
10881088
}else {
10891089
/* Cleanup orphan index entries */
10901090
err=ovl_cleanup(dir,index);

‎fs/overlayfs/super.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -229,6 +229,7 @@ static void ovl_free_fs(struct ovl_fs *ofs)
229229
unsignedi;
230230

231231
dput(ofs->indexdir);
232+
dput(ofs->whiteout);
232233
dput(ofs->workdir);
233234
if (ofs->workdir_locked)
234235
ovl_inuse_unlock(ofs->workbasedir);
@@ -961,6 +962,10 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
961962
if (!ofs->workdir)
962963
gotoout;
963964

965+
err=ovl_make_singleton_whiteout(ofs);
966+
if (err<0)
967+
gotoout;
968+
964969
/*
965970
* Upper should support d_type, else whiteouts are visible. Given
966971
* workdir and upper are on same fs, we can do iterate_dir() on

‎fs/overlayfs/util.c‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -533,8 +533,10 @@ static void ovl_cleanup_index(struct dentry *dentry)
533533
if (IS_ERR(index)) {
534534
index=NULL;
535535
}elseif (ovl_index_all(dentry->d_sb)) {
536+
structovl_fs*ofs=dentry->d_sb->s_fs_info;
537+
536538
/* Whiteout orphan index to block future open by handle */
537-
err=ovl_cleanup_and_whiteout(indexdir,dir,index);
539+
err=ovl_cleanup_and_whiteout(ofs,indexdir,dir,index);
538540
}else {
539541
/* Cleanup orphan index entries */
540542
err=ovl_cleanup(dir,index);

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