Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755206Ab0HHP7A (ORCPT ); Sun, 8 Aug 2010 11:59:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6068 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754878Ab0HHPz0 (ORCPT ); Sun, 8 Aug 2010 11:55:26 -0400 From: Valerie Aurora To: Alexander Viro Cc: Miklos Szeredi , Jan Blunck , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Valerie Aurora Subject: [PATCH 25/39] fallthru: tmpfs fallthru support Date: Sun, 8 Aug 2010 11:52:42 -0400 Message-Id: <1281282776-5447-26-git-send-email-vaurora@redhat.com> In-Reply-To: <1281282776-5447-1-git-send-email-vaurora@redhat.com> References: <1281282776-5447-1-git-send-email-vaurora@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6480 Lines: 201 Add support for fallthru directory entries to tmpfs Signed-off-by: Valerie Aurora --- fs/dcache.c | 3 +- fs/libfs.c | 23 ++++++++++++++++++-- mm/shmem.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++------- 3 files changed, 78 insertions(+), 12 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index ed7f15a..4fe51a9 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2254,7 +2254,8 @@ resume: * we can evict it. */ if (d_unhashed(dentry)||(!dentry->d_inode && - !d_is_whiteout(dentry))) + !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 dcaf972..1172f1a 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -130,6 +130,7 @@ 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; + char d_type; int i = filp->f_pos; switch (i) { @@ -155,14 +156,30 @@ 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; spin_unlock(&dcache_lock); + if (d_is_fallthru(next)) { + /* + * Fallthru lookup should never fail on tmpfs (except + * ENOMEM and the like). If fallthru fails, better to + * fake up return values than crash. + */ + ino = 1; + d_type = DT_UNKNOWN; + generic_readdir_fallthru(filp->f_path.dentry, + next->d_name.name, + next->d_name.len, + &ino, &d_type); + } else { + ino = next->d_inode->i_ino; + d_type = dt_type(next->d_inode); + } + 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 a0a4fa5..eab3f27 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1809,8 +1809,7 @@ 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) @@ -1841,8 +1840,10 @@ 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)) { + /* A fallthru for a dir is treated like a regular link */ + if (old_dentry->d_inode && + S_ISDIR(old_dentry->d_inode->i_mode)) shmem_rmdir(dir, old_dentry); else shmem_unlink(dir, old_dentry); @@ -1859,6 +1860,48 @@ 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 in tmpfs is the + * logical equivalent of an in-kernel readdir() cache. It can't be + * deleted until the file system is unmounted. + */ +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)) { @@ -1866,14 +1909,15 @@ 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.. @@ -1955,7 +1999,8 @@ 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) { @@ -2479,8 +2524,10 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent) sb->s_root = root; #ifdef CONFIG_TMPFS - if (!(sb->s_flags & MS_NOUSER)) + if (!(sb->s_flags & MS_NOUSER)) { sb->s_flags |= MS_WHITEOUT; + sb->s_flags |= MS_FALLTHRU; + } #endif return 0; @@ -2583,6 +2630,7 @@ 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, -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/