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![Theodore Ts'o](/assets/img/avatar_default.png)
Previously, the no-op "mount -o mount /dev/xxx" operation when the file system is already mounted read-write causes an implied, unconditional syncfs(). This seems pretty stupid, and it's certainly documented or guaraunteed to do this, nor is it particularly useful, except in the case where the file system was mounted rw and is getting remounted read-only. However, it's possible that there might be some file systems that are actually depending on this behavior. In most file systems, it's probably fine to only call sync_filesystem() when transitioning from read-write to read-only, and there are some file systems where this is not needed at all (for example, for a pseudo-filesystem or something like romfs). Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Evgeniy Dushistov <dushistov@mail.ru> Cc: Jan Kara <jack@suse.cz> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Anders Larsen <al@alarsen.net> Cc: Phillip Lougher <phillip@squashfs.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Cc: Petr Vandrovec <petr@vandrovec.name> Cc: xfs@oss.sgi.com Cc: linux-btrfs@vger.kernel.org Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: codalist@coda.cs.cmu.edu Cc: linux-ext4@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: fuse-devel@lists.sourceforge.net Cc: cluster-devel@redhat.com Cc: linux-mtd@lists.infradead.org Cc: jfs-discussion@lists.sourceforge.net Cc: linux-nfs@vger.kernel.org Cc: linux-nilfs@vger.kernel.org Cc: linux-ntfs-dev@lists.sourceforge.net Cc: ocfs2-devel@oss.oracle.com Cc: reiserfs-devel@vger.kernel.org
293 lines
7.3 KiB
C
293 lines
7.3 KiB
C
/*
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* Copyright (c) 2000-2001 Christoph Hellwig.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification.
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* 2. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL").
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Veritas filesystem driver - superblock related routines.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/blkdev.h>
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/vfs.h>
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#include <linux/mount.h>
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#include "vxfs.h"
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#include "vxfs_extern.h"
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#include "vxfs_dir.h"
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#include "vxfs_inode.h"
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MODULE_AUTHOR("Christoph Hellwig");
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MODULE_DESCRIPTION("Veritas Filesystem (VxFS) driver");
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MODULE_LICENSE("Dual BSD/GPL");
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static void vxfs_put_super(struct super_block *);
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static int vxfs_statfs(struct dentry *, struct kstatfs *);
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static int vxfs_remount(struct super_block *, int *, char *);
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static const struct super_operations vxfs_super_ops = {
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.evict_inode = vxfs_evict_inode,
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.put_super = vxfs_put_super,
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.statfs = vxfs_statfs,
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.remount_fs = vxfs_remount,
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};
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/**
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* vxfs_put_super - free superblock resources
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* @sbp: VFS superblock.
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*
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* Description:
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* vxfs_put_super frees all resources allocated for @sbp
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* after the last instance of the filesystem is unmounted.
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*/
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static void
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vxfs_put_super(struct super_block *sbp)
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{
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struct vxfs_sb_info *infp = VXFS_SBI(sbp);
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vxfs_put_fake_inode(infp->vsi_fship);
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vxfs_put_fake_inode(infp->vsi_ilist);
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vxfs_put_fake_inode(infp->vsi_stilist);
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brelse(infp->vsi_bp);
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kfree(infp);
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}
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/**
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* vxfs_statfs - get filesystem information
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* @dentry: VFS dentry to locate superblock
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* @bufp: output buffer
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*
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* Description:
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* vxfs_statfs fills the statfs buffer @bufp with information
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* about the filesystem described by @dentry.
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*
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* Returns:
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* Zero.
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*
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* Locking:
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* No locks held.
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*
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* Notes:
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* This is everything but complete...
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*/
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static int
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vxfs_statfs(struct dentry *dentry, struct kstatfs *bufp)
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{
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struct vxfs_sb_info *infp = VXFS_SBI(dentry->d_sb);
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bufp->f_type = VXFS_SUPER_MAGIC;
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bufp->f_bsize = dentry->d_sb->s_blocksize;
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bufp->f_blocks = infp->vsi_raw->vs_dsize;
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bufp->f_bfree = infp->vsi_raw->vs_free;
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bufp->f_bavail = 0;
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bufp->f_files = 0;
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bufp->f_ffree = infp->vsi_raw->vs_ifree;
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bufp->f_namelen = VXFS_NAMELEN;
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return 0;
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}
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static int vxfs_remount(struct super_block *sb, int *flags, char *data)
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{
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sync_filesystem(sb);
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*flags |= MS_RDONLY;
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return 0;
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}
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/**
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* vxfs_read_super - read superblock into memory and initialize filesystem
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* @sbp: VFS superblock (to fill)
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* @dp: fs private mount data
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* @silent: do not complain loudly when sth is wrong
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*
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* Description:
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* We are called on the first mount of a filesystem to read the
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* superblock into memory and do some basic setup.
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*
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* Returns:
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* The superblock on success, else %NULL.
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*
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* Locking:
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* We are under @sbp->s_lock.
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*/
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static int vxfs_fill_super(struct super_block *sbp, void *dp, int silent)
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{
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struct vxfs_sb_info *infp;
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struct vxfs_sb *rsbp;
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struct buffer_head *bp = NULL;
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u_long bsize;
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struct inode *root;
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int ret = -EINVAL;
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sbp->s_flags |= MS_RDONLY;
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infp = kzalloc(sizeof(*infp), GFP_KERNEL);
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if (!infp) {
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printk(KERN_WARNING "vxfs: unable to allocate incore superblock\n");
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return -ENOMEM;
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}
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bsize = sb_min_blocksize(sbp, BLOCK_SIZE);
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if (!bsize) {
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printk(KERN_WARNING "vxfs: unable to set blocksize\n");
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goto out;
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}
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bp = sb_bread(sbp, 1);
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if (!bp || !buffer_mapped(bp)) {
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if (!silent) {
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printk(KERN_WARNING
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"vxfs: unable to read disk superblock\n");
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}
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goto out;
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}
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rsbp = (struct vxfs_sb *)bp->b_data;
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if (rsbp->vs_magic != VXFS_SUPER_MAGIC) {
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if (!silent)
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printk(KERN_NOTICE "vxfs: WRONG superblock magic\n");
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goto out;
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}
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if ((rsbp->vs_version < 2 || rsbp->vs_version > 4) && !silent) {
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printk(KERN_NOTICE "vxfs: unsupported VxFS version (%d)\n",
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rsbp->vs_version);
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goto out;
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}
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#ifdef DIAGNOSTIC
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printk(KERN_DEBUG "vxfs: supported VxFS version (%d)\n", rsbp->vs_version);
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printk(KERN_DEBUG "vxfs: blocksize: %d\n", rsbp->vs_bsize);
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#endif
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sbp->s_magic = rsbp->vs_magic;
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sbp->s_fs_info = infp;
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infp->vsi_raw = rsbp;
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infp->vsi_bp = bp;
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infp->vsi_oltext = rsbp->vs_oltext[0];
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infp->vsi_oltsize = rsbp->vs_oltsize;
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if (!sb_set_blocksize(sbp, rsbp->vs_bsize)) {
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printk(KERN_WARNING "vxfs: unable to set final block size\n");
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goto out;
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}
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if (vxfs_read_olt(sbp, bsize)) {
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printk(KERN_WARNING "vxfs: unable to read olt\n");
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goto out;
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}
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if (vxfs_read_fshead(sbp)) {
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printk(KERN_WARNING "vxfs: unable to read fshead\n");
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goto out;
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}
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sbp->s_op = &vxfs_super_ops;
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root = vxfs_iget(sbp, VXFS_ROOT_INO);
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if (IS_ERR(root)) {
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ret = PTR_ERR(root);
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goto out;
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}
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sbp->s_root = d_make_root(root);
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if (!sbp->s_root) {
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printk(KERN_WARNING "vxfs: unable to get root dentry.\n");
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goto out_free_ilist;
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}
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return 0;
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out_free_ilist:
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vxfs_put_fake_inode(infp->vsi_fship);
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vxfs_put_fake_inode(infp->vsi_ilist);
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vxfs_put_fake_inode(infp->vsi_stilist);
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out:
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brelse(bp);
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kfree(infp);
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return ret;
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}
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/*
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* The usual module blurb.
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*/
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static struct dentry *vxfs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_bdev(fs_type, flags, dev_name, data, vxfs_fill_super);
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}
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static struct file_system_type vxfs_fs_type = {
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.owner = THIS_MODULE,
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.name = "vxfs",
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.mount = vxfs_mount,
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.kill_sb = kill_block_super,
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.fs_flags = FS_REQUIRES_DEV,
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};
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MODULE_ALIAS_FS("vxfs"); /* makes mount -t vxfs autoload the module */
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MODULE_ALIAS("vxfs");
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static int __init
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vxfs_init(void)
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{
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int rv;
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vxfs_inode_cachep = kmem_cache_create("vxfs_inode",
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sizeof(struct vxfs_inode_info), 0,
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SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
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if (!vxfs_inode_cachep)
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return -ENOMEM;
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rv = register_filesystem(&vxfs_fs_type);
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if (rv < 0)
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kmem_cache_destroy(vxfs_inode_cachep);
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return rv;
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}
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static void __exit
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vxfs_cleanup(void)
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{
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unregister_filesystem(&vxfs_fs_type);
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/*
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* Make sure all delayed rcu free inodes are flushed before we
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* destroy cache.
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*/
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rcu_barrier();
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kmem_cache_destroy(vxfs_inode_cachep);
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}
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module_init(vxfs_init);
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module_exit(vxfs_cleanup);
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