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Message-Id: <1256152779-10054-14-git-send-email-vaurora@redhat.com>
Date: Wed, 21 Oct 2009 12:19:11 -0700
From: Valerie Aurora <vaurora@...hat.com>
To: Jan Blunck <jblunck@...e.de>,
Alexander Viro <viro@...iv.linux.org.uk>,
Christoph Hellwig <hch@...radead.org>,
Andy Whitcroft <apw@...onical.com>,
Scott James Remnant <scott@...onical.com>,
Sandu Popa Marius <sandupopamarius@...il.com>,
Jan Rekorajski <baggins@...h.mimuw.edu.pl>,
"J. R. Okajima" <hooanon05@...oo.co.jp>,
Arnd Bergmann <arnd@...db.de>,
Vladimir Dronnikov <dronnikov@...il.com>,
Felix Fietkau <nbd@...nwrt.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Jan Blunck <jblunck@...e.de>,
David Woodhouse <dwmw2@...radead.org>
Subject: [PATCH 13/41] whiteout: tmpfs whiteout support
From: Jan Blunck <jblunck@...e.de>
Add support for whiteout dentries to tmpfs.
XXX - Not sure this is the right patch to put the code for supporting
whiteouts in d_genocide().
Signed-off-by: Jan Blunck <jblunck@...e.de>
Signed-off-by: David Woodhouse <dwmw2@...radead.org>
Signed-off-by: Valerie Aurora <vaurora@...hat.com>
---
fs/dcache.c | 3 +-
mm/shmem.c | 149 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 137 insertions(+), 15 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 0fcae4b..1fae1df 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2280,7 +2280,8 @@ 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)))
continue;
if (!list_empty(&dentry->d_subdirs)) {
this_parent = dentry;
diff --git a/mm/shmem.c b/mm/shmem.c
index d713239..2faa14b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1794,6 +1794,76 @@ static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
return 0;
}
+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().
+ */
+static int shmem_whiteout(struct inode *dir, struct dentry *old_dentry,
+ struct dentry *new_dentry)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(dir->i_sb);
+ struct dentry *dentry;
+
+ if (!(dir->i_sb->s_flags & MS_WHITEOUT))
+ return -EPERM;
+
+ /* This gives us a proper initialized negative dentry */
+ dentry = simple_lookup(dir, new_dentry, NULL);
+ if (dentry && IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ /*
+ * No ordinary (disk based) filesystem counts whiteouts as inodes;
+ * but 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);
+ }
+
+ if (old_dentry->d_inode) {
+ if (S_ISDIR(old_dentry->d_inode->i_mode))
+ shmem_rmdir(dir, old_dentry);
+ else
+ shmem_unlink(dir, old_dentry);
+ }
+
+ dir->i_size += BOGO_DIRENT_SIZE;
+ dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ /* Extra pinning count for the created dentry */
+ dget(new_dentry);
+ spin_lock(&new_dentry->d_lock);
+ new_dentry->d_flags |= DCACHE_WHITEOUT;
+ spin_unlock(&new_dentry->d_lock);
+ return 0;
+}
+
+static void shmem_d_instantiate(struct inode *dir, struct dentry *dentry,
+ struct inode *inode)
+{
+ if (d_is_whiteout(dentry)) {
+ /* Re-using an existing whiteout */
+ shmem_free_inode(dir->i_sb);
+ if (S_ISDIR(inode->i_mode))
+ inode->i_mode |= S_OPAQUE;
+ } else {
+ /* New dentry */
+ dir->i_size += BOGO_DIRENT_SIZE;
+ dget(dentry); /* Extra count - pin the dentry in core */
+ }
+ /* Will clear DCACHE_WHITEOUT flag */
+ d_instantiate(dentry, inode);
+
+}
/*
* File creation. Allocate an inode, and we're done..
*/
@@ -1823,10 +1893,10 @@ shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
if (S_ISDIR(mode))
inode->i_mode |= S_ISGID;
}
- dir->i_size += BOGO_DIRENT_SIZE;
+
+ shmem_d_instantiate(dir, dentry, inode);
+
dir->i_ctime = dir->i_mtime = CURRENT_TIME;
- d_instantiate(dentry, inode);
- dget(dentry); /* Extra count - pin the dentry in core */
}
return error;
}
@@ -1864,12 +1934,11 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentr
if (ret)
goto out;
- dir->i_size += BOGO_DIRENT_SIZE;
+ shmem_d_instantiate(dir, dentry, inode);
+
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
inc_nlink(inode);
atomic_inc(&inode->i_count); /* New dentry reference */
- dget(dentry); /* Extra pinning count for the created dentry */
- d_instantiate(dentry, inode);
out:
return ret;
}
@@ -1878,21 +1947,61 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
- if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
- shmem_free_inode(inode->i_sb);
+ if (d_is_whiteout(dentry) || (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)))
+ shmem_free_inode(dir->i_sb);
+ if (inode) {
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ drop_nlink(inode);
+ }
dir->i_size -= BOGO_DIRENT_SIZE;
- inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
- drop_nlink(inode);
dput(dentry); /* Undo the count from "create" - this does all the work */
return 0;
}
+static void shmem_dir_unlink_whiteouts(struct inode *dir, struct dentry *dentry)
+{
+ if (!dentry->d_inode)
+ return;
+
+ /* Remove whiteouts from logical empty directory */
+ if (S_ISDIR(dentry->d_inode->i_mode) &&
+ dentry->d_inode->i_sb->s_flags & MS_WHITEOUT) {
+ struct dentry *child, *next;
+ LIST_HEAD(list);
+
+ 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)) {
+ __d_drop(child);
+ if (!list_empty(&child->d_lru)) {
+ list_del(&child->d_lru);
+ dentry_stat.nr_unused--;
+ }
+ list_add(&child->d_lru, &list);
+ }
+ spin_unlock(&child->d_lock);
+ }
+ spin_unlock(&dcache_lock);
+
+ list_for_each_entry_safe(child, next, &list, d_lru) {
+ spin_lock(&child->d_lock);
+ list_del_init(&child->d_lru);
+ spin_unlock(&child->d_lock);
+
+ shmem_unlink(dentry->d_inode, child);
+ }
+ }
+}
+
static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
{
if (!simple_empty(dentry))
return -ENOTEMPTY;
+ /* Remove whiteouts from logical empty directory */
+ shmem_dir_unlink_whiteouts(dir, dentry);
drop_nlink(dentry->d_inode);
drop_nlink(dir);
return shmem_unlink(dir, dentry);
@@ -1901,7 +2010,7 @@ static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
/*
* The VFS layer already does all the dentry stuff for rename,
* we just have to decrement the usage count for the target if
- * it exists so that the VFS layer correctly free's it when it
+ * it exists so that the VFS layer correctly frees it when it
* gets overwritten.
*/
static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
@@ -1912,7 +2021,12 @@ static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
+ if (d_is_whiteout(new_dentry))
+ shmem_unlink(new_dir, new_dentry);
+
if (new_dentry->d_inode) {
+ /* Remove whiteouts from logical empty directory */
+ shmem_dir_unlink_whiteouts(new_dir, new_dentry);
(void) shmem_unlink(new_dir, new_dentry);
if (they_are_dirs)
drop_nlink(old_dir);
@@ -1977,12 +2091,12 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
set_page_dirty(page);
page_cache_release(page);
}
+
+ shmem_d_instantiate(dir, dentry, inode);
+
if (dir->i_mode & S_ISGID)
inode->i_gid = dir->i_gid;
- dir->i_size += BOGO_DIRENT_SIZE;
dir->i_ctime = dir->i_mtime = CURRENT_TIME;
- d_instantiate(dentry, inode);
- dget(dentry);
return 0;
}
@@ -2363,6 +2477,12 @@ static int shmem_fill_super(struct super_block *sb,
if (!root)
goto failed_iput;
sb->s_root = root;
+
+#ifdef CONFIG_TMPFS
+ if (!(sb->s_flags & MS_NOUSER))
+ sb->s_flags |= MS_WHITEOUT;
+#endif
+
return 0;
failed_iput:
@@ -2462,6 +2582,7 @@ static const struct inode_operations shmem_dir_inode_operations = {
.rmdir = shmem_rmdir,
.mknod = shmem_mknod,
.rename = shmem_rename,
+ .whiteout = shmem_whiteout,
#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_notify_change,
--
1.6.3.3
--
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