commit afc64c23debd41453b351ac8d37cb0a8a3793a38
Author: Erez Zadok <[EMAIL PROTECTED]>
Date: Wed Jan 9 17:00:48 2008 -0500
Unionfs: branch-management related locking fixes
Add necessary locking to dentry/inode branch-configuration, so we get
consistent values during branch-management actions. In d_revalidate_chain,
->permission, and ->create, also lock parent dentry.
diff --git a/fs/unionfs/commonfops.c b/fs/unionfs/commonfops.c
index 0637ec0..dbea587 100644
--- a/fs/unionfs/commonfops.c
+++ b/fs/unionfs/commonfops.c
@@ -317,6 +317,7 @@ int unionfs_file_revalidate(struct file *file, bool
willwrite)
* First revalidate the dentry inside struct file,
* but not unhashed dentries.
*/
+reval_dentry:
if (unlikely(!d_deleted(dentry) &&
!__unionfs_d_revalidate_chain(dentry, NULL, willwrite))) {
err = -ESTALE;
@@ -327,6 +328,11 @@ int unionfs_file_revalidate(struct file *file, bool
willwrite)
dgen = atomic_read(&UNIONFS_D(dentry)->generation);
fgen = atomic_read(&UNIONFS_F(file)->generation);
+ if (unlikely(sbgen > dgen)) {
+ pr_debug("unionfs: retry dentry revalidation\n");
+ schedule();
+ goto reval_dentry;
+ }
BUG_ON(sbgen > dgen);
/*
diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index 971605f..ad3cc9a 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -196,7 +196,7 @@ bool is_newer_lower(const struct dentry *dentry)
if (!dentry || !UNIONFS_D(dentry))
return false;
inode = dentry->d_inode;
- if (!inode || !UNIONFS_I(inode) ||
+ if (!inode || !UNIONFS_I(inode)->lower_inodes ||
ibstart(inode) < 0 || ibend(inode) < 0)
return false;
@@ -290,6 +290,8 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry,
struct nameidata *nd,
chain_len = 0;
sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
dtmp = dentry->d_parent;
+ if (dentry != dtmp)
+ unionfs_lock_dentry(dtmp, UNIONFS_DMUTEX_REVAL_PARENT);
dgen = atomic_read(&UNIONFS_D(dtmp)->generation);
/* XXX: should we check if is_newer_lower all the way up? */
if (unlikely(is_newer_lower(dtmp))) {
@@ -310,6 +312,8 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry,
struct nameidata *nd,
}
purge_inode_data(dtmp->d_inode);
}
+ if (dentry != dtmp)
+ unionfs_unlock_dentry(dtmp);
while (sbgen != dgen) {
/* The root entry should always be valid */
BUG_ON(IS_ROOT(dtmp));
diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index 2af8957..cfa04bf 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -29,6 +29,13 @@ static int unionfs_create(struct inode *parent, struct
dentry *dentry,
int valid = 0;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
+ unionfs_lock_dentry(dentry->d_parent, UNIONFS_DMUTEX_PARENT);
+ valid = __unionfs_d_revalidate_chain(dentry->d_parent, nd, false);
+ unionfs_unlock_dentry(dentry->d_parent);
+ if (unlikely(!valid)) {
+ err = -ESTALE; /* same as what real_lookup does */
+ goto out;
+ }
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate_chain(dentry, nd, false);
@@ -925,6 +932,14 @@ static int unionfs_permission(struct inode *inode, int
mask,
const int is_file = !S_ISDIR(inode->i_mode);
const int write_mask = (mask & MAY_WRITE) && !(mask & MAY_READ);
+ if (nd)
+ unionfs_lock_dentry(nd->dentry, UNIONFS_DMUTEX_CHILD);
+
+ if (!UNIONFS_I(inode)->lower_inodes) {
+ if (is_file) /* dirs can be unlinked but chdir'ed to */
+ err = -ESTALE; /* force revalidate */
+ goto out;
+ }
bstart = ibstart(inode);
bend = ibend(inode);
if (unlikely(bstart < 0 || bend < 0)) {
@@ -991,6 +1006,8 @@ static int unionfs_permission(struct inode *inode, int
mask,
out:
unionfs_check_inode(inode);
+ if (nd)
+ unionfs_unlock_dentry(nd->dentry);
return err;
}
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