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dentry_kill(): don't try to remove from shrink list 

If the victim in on the shrink list, don't remove it from there.
If shrink_dentry_list() manages to remove it from the list before
we are done - fine, we'll just free it as usual.  If not - mark
it with new flag (DCACHE_MAY_FREE) and leave it there.

Eventually, shrink_dentry_list() will get to it, remove the sucker
from shrink list and call dentry_kill(dentry, 0).  Which is where
we'll deal with freeing.

Since now dentry_kill(dentry, 0) may happen after or during
dentry_kill(dentry, 1), we need to recognize that (by seeing
DCACHE_DENTRY_KILLED already set), unlock everything
and either free the sucker (in case DCACHE_MAY_FREE has been
set) or leave it for ongoing dentry_kill(dentry, 1) to deal with.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-05-01 10:30:00 -04:00
parent 01b6035190
commit 41edf278fc
2 changed files with 21 additions and 8 deletions
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27
fs/dcache.c
View File

@ -468,7 +468,14 @@ dentry_kill(struct dentry *dentry, int unlock_on_failure)
__releases(dentry->d_lock)
{
struct inode *inode;
struct dentry *parent;
struct dentry *parent = NULL;
bool can_free = true;
if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
can_free = dentry->d_flags & DCACHE_MAY_FREE;
spin_unlock(&dentry->d_lock);
goto out;
}
inode = dentry->d_inode;
if (inode && !spin_trylock(&inode->i_lock)) {
@ -479,9 +486,7 @@ relock:
}
return dentry; /* try again with same dentry */
}
if (IS_ROOT(dentry))
parent = NULL;
else
if (!IS_ROOT(dentry))
parent = dentry->d_parent;
if (parent && !spin_trylock(&parent->d_lock)) {
if (inode)
@ -504,8 +509,6 @@ relock:
if (dentry->d_flags & DCACHE_LRU_LIST) {
if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
d_lru_del(dentry);
else
d_shrink_del(dentry);
}
/* if it was on the hash then remove it */
__d_drop(dentry);
@ -527,7 +530,15 @@ relock:
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
dentry_free(dentry);
spin_lock(&dentry->d_lock);
if (dentry->d_flags & DCACHE_SHRINK_LIST) {
dentry->d_flags |= DCACHE_MAY_FREE;
can_free = false;
}
spin_unlock(&dentry->d_lock);
out:
if (likely(can_free))
dentry_free(dentry);
return parent;
}
@ -829,7 +840,7 @@ static void shrink_dentry_list(struct list_head *list)
* We found an inuse dentry which was not removed from
* the LRU because of laziness during lookup. Do not free it.
*/
if (dentry->d_lockref.count) {
if ((int)dentry->d_lockref.count > 0) {
spin_unlock(&dentry->d_lock);
continue;
}

2
include/linux/dcache.h
View File

@ -221,6 +221,8 @@ struct dentry_operations {
#define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */
#define DCACHE_FILE_TYPE 0x00400000 /* Other file type */
#define DCACHE_MAY_FREE 0x00800000
extern seqlock_t rename_lock;
static inline int dname_external(const struct dentry *dentry)