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Registered in England and Wales under Company Registration No. 3798903 From: David Howells Subject: [PATCH 17/73] tmpfs: Add fallthru support [ver #2] To: linux-fsdevel@vger.kernel.org, viro@ZenIV.linux.org.uk, valerie.aurora@gmail.com Cc: linux-kernel@vger.kernel.org, David Howells Date: Tue, 21 Feb 2012 17:59:39 +0000 Message-ID: <20120221175939.25235.65321.stgit@warthog.procyon.org.uk> In-Reply-To: <20120221175721.25235.8901.stgit@warthog.procyon.org.uk> References: <20120221175721.25235.8901.stgit@warthog.procyon.org.uk> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6405 Lines: 200 From: Valerie Aurora Add support for fallthru directory entries to tmpfs. Original-author: Valerie Aurora Signed-off-by: David Howells --- fs/dcache.c | 4 +++- fs/libfs.c | 16 ++++++++++++--- mm/shmem.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++------- 3 files changed, 72 insertions(+), 12 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index b1ce8d1..238684a 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2896,7 +2896,9 @@ resume: * can evict it. */ if (d_unhashed(dentry) || - (!dentry->d_inode && !d_is_whiteout(dentry))) { + (!dentry->d_inode && + !d_is_whiteout(dentry) && + !d_is_fallthru(dentry))) { spin_unlock(&dentry->d_lock); continue; } diff --git a/fs/libfs.c b/fs/libfs.c index 38eb46d..43f1ac2 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -141,6 +141,7 @@ 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) { @@ -167,17 +168,26 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) struct dentry *next; next = list_entry(p, struct dentry, d_u.d_child); spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); - if (!simple_positive(next)) { + if (d_unhashed(next) || + (!next->d_inode && !d_is_fallthru(next))) { spin_unlock(&next->d_lock); continue; } spin_unlock(&next->d_lock); spin_unlock(&dentry->d_lock); + if (d_is_fallthru(next)) { + /* XXX placeholder until generic_readdir_fallthru() arrives */ + ino = 1; + d_type = DT_UNKNOWN; + } 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(&dentry->d_lock); spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); diff --git a/mm/shmem.c b/mm/shmem.c index ca0bd30..bfd9ac8 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1481,8 +1481,7 @@ 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) @@ -1513,8 +1512,10 @@ 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); @@ -1531,6 +1532,48 @@ 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)) { @@ -1538,14 +1581,15 @@ 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.. @@ -1627,7 +1671,8 @@ 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) { @@ -2347,8 +2392,10 @@ 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; @@ -2451,6 +2498,7 @@ 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_XATTR .setxattr = shmem_setxattr, -- 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/