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Message-Id: <1242662968-11684-32-git-send-email-jblunck@suse.de>
Date: Mon, 18 May 2009 18:09:27 +0200
From: Jan Blunck <jblunck@...e.de>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: viro@...iv.linux.org.uk, bharata@...ibm.com, dwmw2@...radead.org,
mszeredi@...e.cz, vaurora@...hat.com
Subject: [PATCH 31/32] union-mount: tmpfs fallthru support
From: Valerie Aurora (Henson) <vaurora@...hat.com>
Add support for fallthru entries to tmpfs.
Signed-off-by: Valerie Aurora (Henson) <vaurora@...hat.com>
---
fs/dcache.c | 4 ++-
fs/libfs.c | 18 ++++++++++++++--
mm/shmem.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++-------
3 files changed, 71 insertions(+), 12 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 844a76a..2d4c24e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2305,7 +2305,9 @@ resume:
struct list_head *tmp = next;
struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
next = tmp->next;
- if (d_unhashed(dentry)||!dentry->d_inode)
+ if (d_unhashed(dentry)||(!dentry->d_inode &&
+ !d_is_whiteout(dentry) &&
+ !d_is_fallthru(dentry)))
continue;
if (!list_empty(&dentry->d_subdirs)) {
this_parent = dentry;
diff --git a/fs/libfs.c b/fs/libfs.c
index 49b4409..a362077 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -131,6 +131,7 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
struct dentry *cursor = filp->private_data;
struct list_head *p, *q = &cursor->d_u.d_child;
ino_t ino;
+ int d_type;
int i = filp->f_pos;
switch (i) {
@@ -156,14 +157,25 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
struct dentry *next;
next = list_entry(p, struct dentry, d_u.d_child);
- if (d_unhashed(next) || !next->d_inode)
+ if (d_unhashed(next) || (!next->d_inode && !d_is_fallthru(next)))
continue;
+ if (d_is_fallthru(next)) {
+ /* XXX Make up things we can
+ * only get out of the inode.
+ * Should probably really do a
+ * lookup instead. */
+ ino = 100; /* XXX Made up number of no significance */
+ d_type = DT_UNKNOWN;
+ } else {
+ ino = next->d_inode->i_ino;
+ d_type = dt_type(next->d_inode);
+ }
+
spin_unlock(&dcache_lock);
if (filldir(dirent, next->d_name.name,
next->d_name.len, filp->f_pos,
- next->d_inode->i_ino,
- dt_type(next->d_inode)) < 0)
+ ino, d_type) < 0)
return 0;
spin_lock(&dcache_lock);
/* next is still alive */
diff --git a/mm/shmem.c b/mm/shmem.c
index b2e3904..f8284ea 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1778,8 +1778,7 @@ static int shmem_rmdir(struct inode *dir, struct dentry *dentry);
static int shmem_unlink(struct inode *dir, struct dentry *dentry);
/*
- * This is the whiteout support for tmpfs. It uses one singleton whiteout
- * inode per superblock thus it is very similar to shmem_link().
+ * Create a dentry to signify a whiteout.
*/
static int shmem_whiteout(struct inode *dir, struct dentry *old_dentry,
struct dentry *new_dentry)
@@ -1810,8 +1809,8 @@ static int shmem_whiteout(struct inode *dir, struct dentry *old_dentry,
spin_unlock(&sbinfo->stat_lock);
}
- if (old_dentry->d_inode) {
- if (S_ISDIR(old_dentry->d_inode->i_mode))
+ if (old_dentry->d_inode || d_is_fallthru(old_dentry)) {
+ if (old_dentry->d_inode && S_ISDIR(old_dentry->d_inode->i_mode))
shmem_rmdir(dir, old_dentry);
else
shmem_unlink(dir, old_dentry);
@@ -1828,6 +1827,48 @@ static int shmem_whiteout(struct inode *dir, struct dentry *old_dentry,
}
static void shmem_d_instantiate(struct inode *dir, struct dentry *dentry,
+ struct inode *inode);
+
+/*
+ * Create a dentry to signify a fallthru. A fallthru lets us read the
+ * low-level dentries into the dcache once on the first readdir() and
+ * then
+ */
+static int shmem_fallthru(struct inode *dir, struct dentry *dentry)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(dir->i_sb);
+
+ /* FIXME: this is stupid */
+ if (!(dir->i_sb->s_flags & MS_WHITEOUT))
+ return -EPERM;
+
+ if (dentry->d_inode || d_is_fallthru(dentry) || d_is_whiteout(dentry))
+ return -EEXIST;
+
+ /*
+ * Each new link needs a new dentry, pinning lowmem, and tmpfs
+ * dentries cannot be pruned until they are unlinked.
+ */
+ if (sbinfo->max_inodes) {
+ spin_lock(&sbinfo->stat_lock);
+ if (!sbinfo->free_inodes) {
+ spin_unlock(&sbinfo->stat_lock);
+ return -ENOSPC;
+ }
+ sbinfo->free_inodes--;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+
+ shmem_d_instantiate(dir, dentry, NULL);
+ dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+
+ spin_lock(&dentry->d_lock);
+ dentry->d_flags |= DCACHE_FALLTHRU;
+ spin_unlock(&dentry->d_lock);
+ return 0;
+}
+
+static void shmem_d_instantiate(struct inode *dir, struct dentry *dentry,
struct inode *inode)
{
if (d_is_whiteout(dentry)) {
@@ -1835,14 +1876,15 @@ static void shmem_d_instantiate(struct inode *dir, struct dentry *dentry,
shmem_free_inode(dir->i_sb);
if (S_ISDIR(inode->i_mode))
inode->i_mode |= S_OPAQUE;
+ } else if (d_is_fallthru(dentry)) {
+ shmem_free_inode(dir->i_sb);
} else {
/* New dentry */
dir->i_size += BOGO_DIRENT_SIZE;
dget(dentry); /* Extra count - pin the dentry in core */
}
- /* Will clear DCACHE_WHITEOUT flag */
+ /* Will clear DCACHE_WHITEOUT and DCACHE_FALLTHRU flags */
d_instantiate(dentry, inode);
-
}
/*
* File creation. Allocate an inode, and we're done..
@@ -1928,7 +1970,8 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
- if (d_is_whiteout(dentry) || (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)))
+ if (d_is_whiteout(dentry) || d_is_fallthru(dentry) ||
+ (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)))
shmem_free_inode(dir->i_sb);
if (inode) {
@@ -1954,7 +1997,8 @@ static void shmem_dir_unlink_whiteouts(struct inode *dir, struct dentry *dentry)
spin_lock(&dcache_lock);
list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) {
spin_lock(&child->d_lock);
- if (d_is_whiteout(child)) {
+ /* Unlink fallthrus too */
+ if (d_is_whiteout(child) || d_is_fallthru(child)) {
__d_drop(child);
if (!list_empty(&child->d_lru)) {
list_del(&child->d_lru);
@@ -2569,6 +2613,7 @@ static const struct inode_operations shmem_dir_inode_operations = {
.mknod = shmem_mknod,
.rename = shmem_rename,
.whiteout = shmem_whiteout,
+ .fallthru = shmem_fallthru,
#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_notify_change,
--
1.6.1.3
--
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