1. 根目录:
2. fs
3. xfs
4. libxfs
5. xfs_inode_buf.c

/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_error.h"
#include "xfs_cksum.h"
#include "xfs_icache.h"
#include "xfs_trans.h"
#include "xfs_ialloc.h"

/*
 * Check that none of the inode's in the buffer have a next
 * unlinked field of 0.
 */
#if defined(DEBUG)
void
xfs_inobp_check(
	xfs_mount_t	*mp,
	xfs_buf_t	*bp)
{
	int		i;
	int		j;
	xfs_dinode_t	*dip;

	j = mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog;

	for (i = 0; i < j; i++) {
		dip = (xfs_dinode_t *)xfs_buf_offset(bp,
					i * mp->m_sb.sb_inodesize);
		if (!dip->di_next_unlinked)  {
			xfs_alert(mp,
	"Detected bogus zero next_unlinked field in inode %d buffer 0x%llx.",
				i, (long long)bp->b_bn);
		}
	}
}
#endif

/*
 * If we are doing readahead on an inode buffer, we might be in log recovery
 * reading an inode allocation buffer that hasn't yet been replayed, and hence
 * has not had the inode cores stamped into it. Hence for readahead, the buffer
 * may be potentially invalid.
 *
 * If the readahead buffer is invalid, we don't want to mark it with an error,
 * but we do want to clear the DONE status of the buffer so that a followup read
 * will re-read it from disk. This will ensure that we don't get an unnecessary
 * warnings during log recovery and we don't get unnecssary panics on debug
 * kernels.
 */
static void
xfs_inode_buf_verify(
	struct xfs_buf	*bp,
	bool		readahead)
{
	struct xfs_mount *mp = bp->b_target->bt_mount;
	int		i;
	int		ni;

	/*
	 * Validate the magic number and version of every inode in the buffer
	 */
	ni = XFS_BB_TO_FSB(mp, bp->b_length) * mp->m_sb.sb_inopblock;
	for (i = 0; i < ni; i++) {
		int		di_ok;
		xfs_dinode_t	*dip;

		dip = (struct xfs_dinode *)xfs_buf_offset(bp,
					(i << mp->m_sb.sb_inodelog));
		di_ok = dip->di_magic == cpu_to_be16(XFS_DINODE_MAGIC) &&
			    XFS_DINODE_GOOD_VERSION(dip->di_version);
		if (unlikely(XFS_TEST_ERROR(!di_ok, mp,
						XFS_ERRTAG_ITOBP_INOTOBP,
						XFS_RANDOM_ITOBP_INOTOBP))) {
			if (readahead) {
				bp->b_flags &= ~XBF_DONE;
				return;
			}

			xfs_buf_ioerror(bp, -EFSCORRUPTED);
			xfs_verifier_error(bp);
#ifdef DEBUG
			xfs_alert(mp,
				"bad inode magic/vsn daddr %lld #%d (magic=%x)",
				(unsigned long long)bp->b_bn, i,
				be16_to_cpu(dip->di_magic));
#endif
		}
	}
	xfs_inobp_check(mp, bp);
}


static void
xfs_inode_buf_read_verify(
	struct xfs_buf	*bp)
{
	xfs_inode_buf_verify(bp, false);
}

static void
xfs_inode_buf_readahead_verify(
	struct xfs_buf	*bp)
{
	xfs_inode_buf_verify(bp, true);
}

static void
xfs_inode_buf_write_verify(
	struct xfs_buf	*bp)
{
	xfs_inode_buf_verify(bp, false);
}

const struct xfs_buf_ops xfs_inode_buf_ops = {
	.verify_read = xfs_inode_buf_read_verify,
	.verify_write = xfs_inode_buf_write_verify,
};

const struct xfs_buf_ops xfs_inode_buf_ra_ops = {
	.verify_read = xfs_inode_buf_readahead_verify,
	.verify_write = xfs_inode_buf_write_verify,
};


/*
 * This routine is called to map an inode to the buffer containing the on-disk
 * version of the inode.  It returns a pointer to the buffer containing the
 * on-disk inode in the bpp parameter, and in the dipp parameter it returns a
 * pointer to the on-disk inode within that buffer.
 *
 * If a non-zero error is returned, then the contents of bpp and dipp are
 * undefined.
 */
int
xfs_imap_to_bp(
	struct xfs_mount	*mp,
	struct xfs_trans	*tp,
	struct xfs_imap		*imap,
	struct xfs_dinode       **dipp,
	struct xfs_buf		**bpp,
	uint			buf_flags,
	uint			iget_flags)
{
	struct xfs_buf		*bp;
	int			error;

	buf_flags |= XBF_UNMAPPED;
	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, imap->im_blkno,
				   (int)imap->im_len, buf_flags, &bp,
				   &xfs_inode_buf_ops);
	if (error) {
		if (error == -EAGAIN) {
			ASSERT(buf_flags & XBF_TRYLOCK);
			return error;
		}

		if (error == -EFSCORRUPTED &&
		    (iget_flags & XFS_IGET_UNTRUSTED))
			return -EINVAL;

		xfs_warn(mp, "%s: xfs_trans_read_buf() returned error %d.",
			__func__, error);
		return error;
	}

	*bpp = bp;
	*dipp = (struct xfs_dinode *)xfs_buf_offset(bp, imap->im_boffset);
	return 0;
}

void
xfs_dinode_from_disk(
	xfs_icdinode_t		*to,
	xfs_dinode_t		*from)
{
	to->di_magic = be16_to_cpu(from->di_magic);
	to->di_mode = be16_to_cpu(from->di_mode);
	to->di_version = from ->di_version;
	to->di_format = from->di_format;
	to->di_onlink = be16_to_cpu(from->di_onlink);
	to->di_uid = be32_to_cpu(from->di_uid);
	to->di_gid = be32_to_cpu(from->di_gid);
	to->di_nlink = be32_to_cpu(from->di_nlink);
	to->di_projid_lo = be16_to_cpu(from->di_projid_lo);
	to->di_projid_hi = be16_to_cpu(from->di_projid_hi);
	memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
	to->di_flushiter = be16_to_cpu(from->di_flushiter);
	to->di_atime.t_sec = be32_to_cpu(from->di_atime.t_sec);
	to->di_atime.t_nsec = be32_to_cpu(from->di_atime.t_nsec);
	to->di_mtime.t_sec = be32_to_cpu(from->di_mtime.t_sec);
	to->di_mtime.t_nsec = be32_to_cpu(from->di_mtime.t_nsec);
	to->di_ctime.t_sec = be32_to_cpu(from->di_ctime.t_sec);
	to->di_ctime.t_nsec = be32_to_cpu(from->di_ctime.t_nsec);
	to->di_size = be64_to_cpu(from->di_size);
	to->di_nblocks = be64_to_cpu(from->di_nblocks);
	to->di_extsize = be32_to_cpu(from->di_extsize);
	to->di_nextents = be32_to_cpu(from->di_nextents);
	to->di_anextents = be16_to_cpu(from->di_anextents);
	to->di_forkoff = from->di_forkoff;
	to->di_aformat	= from->di_aformat;
	to->di_dmevmask	= be32_to_cpu(from->di_dmevmask);
	to->di_dmstate	= be16_to_cpu(from->di_dmstate);
	to->di_flags	= be16_to_cpu(from->di_flags);
	to->di_gen	= be32_to_cpu(from->di_gen);

	if (to->di_version == 3) {
		to->di_changecount = be64_to_cpu(from->di_changecount);
		to->di_crtime.t_sec = be32_to_cpu(from->di_crtime.t_sec);
		to->di_crtime.t_nsec = be32_to_cpu(from->di_crtime.t_nsec);
		to->di_flags2 = be64_to_cpu(from->di_flags2);
		to->di_ino = be64_to_cpu(from->di_ino);
		to->di_lsn = be64_to_cpu(from->di_lsn);
		memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
		uuid_copy(&to->di_uuid, &from->di_uuid);
	}
}

void
xfs_dinode_to_disk(
	xfs_dinode_t		*to,
	xfs_icdinode_t		*from)
{
	to->di_magic = cpu_to_be16(from->di_magic);
	to->di_mode = cpu_to_be16(from->di_mode);
	to->di_version = from ->di_version;
	to->di_format = from->di_format;
	to->di_onlink = cpu_to_be16(from->di_onlink);
	to->di_uid = cpu_to_be32(from->di_uid);
	to->di_gid = cpu_to_be32(from->di_gid);
	to->di_nlink = cpu_to_be32(from->di_nlink);
	to->di_projid_lo = cpu_to_be16(from->di_projid_lo);
	to->di_projid_hi = cpu_to_be16(from->di_projid_hi);
	memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
	to->di_atime.t_sec = cpu_to_be32(from->di_atime.t_sec);
	to->di_atime.t_nsec = cpu_to_be32(from->di_atime.t_nsec);
	to->di_mtime.t_sec = cpu_to_be32(from->di_mtime.t_sec);
	to->di_mtime.t_nsec = cpu_to_be32(from->di_mtime.t_nsec);
	to->di_ctime.t_sec = cpu_to_be32(from->di_ctime.t_sec);
	to->di_ctime.t_nsec = cpu_to_be32(from->di_ctime.t_nsec);
	to->di_size = cpu_to_be64(from->di_size);
	to->di_nblocks = cpu_to_be64(from->di_nblocks);
	to->di_extsize = cpu_to_be32(from->di_extsize);
	to->di_nextents = cpu_to_be32(from->di_nextents);
	to->di_anextents = cpu_to_be16(from->di_anextents);
	to->di_forkoff = from->di_forkoff;
	to->di_aformat = from->di_aformat;
	to->di_dmevmask = cpu_to_be32(from->di_dmevmask);
	to->di_dmstate = cpu_to_be16(from->di_dmstate);
	to->di_flags = cpu_to_be16(from->di_flags);
	to->di_gen = cpu_to_be32(from->di_gen);

	if (from->di_version == 3) {
		to->di_changecount = cpu_to_be64(from->di_changecount);
		to->di_crtime.t_sec = cpu_to_be32(from->di_crtime.t_sec);
		to->di_crtime.t_nsec = cpu_to_be32(from->di_crtime.t_nsec);
		to->di_flags2 = cpu_to_be64(from->di_flags2);
		to->di_ino = cpu_to_be64(from->di_ino);
		to->di_lsn = cpu_to_be64(from->di_lsn);
		memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
		uuid_copy(&to->di_uuid, &from->di_uuid);
		to->di_flushiter = 0;
	} else {
		to->di_flushiter = cpu_to_be16(from->di_flushiter);
	}
}

static bool
xfs_dinode_verify(
	struct xfs_mount	*mp,
	struct xfs_inode	*ip,
	struct xfs_dinode	*dip)
{
	if (dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))
		return false;

	/* only version 3 or greater inodes are extensively verified here */
	if (dip->di_version < 3)
		return true;

	if (!xfs_sb_version_hascrc(&mp->m_sb))
		return false;
	if (!xfs_verify_cksum((char *)dip, mp->m_sb.sb_inodesize,
			      XFS_DINODE_CRC_OFF))
		return false;
	if (be64_to_cpu(dip->di_ino) != ip->i_ino)
		return false;
	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_uuid))
		return false;
	return true;
}

void
xfs_dinode_calc_crc(
	struct xfs_mount	*mp,
	struct xfs_dinode	*dip)
{
	__uint32_t		crc;

	if (dip->di_version < 3)
		return;

	ASSERT(xfs_sb_version_hascrc(&mp->m_sb));
	crc = xfs_start_cksum((char *)dip, mp->m_sb.sb_inodesize,
			      XFS_DINODE_CRC_OFF);
	dip->di_crc = xfs_end_cksum(crc);
}

/*
 * Read the disk inode attributes into the in-core inode structure.
 *
 * For version 5 superblocks, if we are initialising a new inode and we are not
 * utilising the XFS_MOUNT_IKEEP inode cluster mode, we can simple build the new
 * inode core with a random generation number. If we are keeping inodes around,
 * we need to read the inode cluster to get the existing generation number off
 * disk. Further, if we are using version 4 superblocks (i.e. v1/v2 inode
 * format) then log recovery is dependent on the di_flushiter field being
 * initialised from the current on-disk value and hence we must also read the
 * inode off disk.
 */
int
xfs_iread(
	xfs_mount_t	*mp,
	xfs_trans_t	*tp,
	xfs_inode_t	*ip,
	uint		iget_flags)
{
	xfs_buf_t	*bp;
	xfs_dinode_t	*dip;
	int		error;

	/*
	 * Fill in the location information in the in-core inode.
	 */
	error = xfs_imap(mp, tp, ip->i_ino, &ip->i_imap, iget_flags);
	if (error)
		return error;

	/* shortcut IO on inode allocation if possible */
	if ((iget_flags & XFS_IGET_CREATE) &&
	    xfs_sb_version_hascrc(&mp->m_sb) &&
	    !(mp->m_flags & XFS_MOUNT_IKEEP)) {
		/* initialise the on-disk inode core */
		memset(&ip->i_d, 0, sizeof(ip->i_d));
		ip->i_d.di_magic = XFS_DINODE_MAGIC;
		ip->i_d.di_gen = prandom_u32();
		if (xfs_sb_version_hascrc(&mp->m_sb)) {
			ip->i_d.di_version = 3;
			ip->i_d.di_ino = ip->i_ino;
			uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
		} else
			ip->i_d.di_version = 2;
		return 0;
	}

	/*
	 * Get pointers to the on-disk inode and the buffer containing it.
	 */
	error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &bp, 0, iget_flags);
	if (error)
		return error;

	/* even unallocated inodes are verified */
	if (!xfs_dinode_verify(mp, ip, dip)) {
		xfs_alert(mp, "%s: validation failed for inode %lld failed",
				__func__, ip->i_ino);

		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, dip);
		error = -EFSCORRUPTED;
		goto out_brelse;
	}

	/*
	 * If the on-disk inode is already linked to a directory
	 * entry, copy all of the inode into the in-core inode.
	 * xfs_iformat_fork() handles copying in the inode format
	 * specific information.
	 * Otherwise, just get the truly permanent information.
	 */
	if (dip->di_mode) {
		xfs_dinode_from_disk(&ip->i_d, dip);
		error = xfs_iformat_fork(ip, dip);
		if (error)  {
#ifdef DEBUG
			xfs_alert(mp, "%s: xfs_iformat() returned error %d",
				__func__, error);
#endif /* DEBUG */
			goto out_brelse;
		}
	} else {
		/*
		 * Partial initialisation of the in-core inode. Just the bits
		 * that xfs_ialloc won't overwrite or relies on being correct.
		 */
		ip->i_d.di_magic = be16_to_cpu(dip->di_magic);
		ip->i_d.di_version = dip->di_version;
		ip->i_d.di_gen = be32_to_cpu(dip->di_gen);
		ip->i_d.di_flushiter = be16_to_cpu(dip->di_flushiter);

		if (dip->di_version == 3) {
			ip->i_d.di_ino = be64_to_cpu(dip->di_ino);
			uuid_copy(&ip->i_d.di_uuid, &dip->di_uuid);
		}

		/*
		 * Make sure to pull in the mode here as well in
		 * case the inode is released without being used.
		 * This ensures that xfs_inactive() will see that
		 * the inode is already free and not try to mess
		 * with the uninitialized part of it.
		 */
		ip->i_d.di_mode = 0;
	}

	/*
	 * Automatically convert version 1 inode formats in memory to version 2
	 * inode format. If the inode is modified, it will get logged and
	 * rewritten as a version 2 inode. We can do this because we set the
	 * superblock feature bit for v2 inodes unconditionally during mount
	 * and it means the reast of the code can assume the inode version is 2
	 * or higher.
	 */
	if (ip->i_d.di_version == 1) {
		ip->i_d.di_version = 2;
		memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
		ip->i_d.di_nlink = ip->i_d.di_onlink;
		ip->i_d.di_onlink = 0;
		xfs_set_projid(ip, 0);
	}

	ip->i_delayed_blks = 0;

	/*
	 * Mark the buffer containing the inode as something to keep
	 * around for a while.  This helps to keep recently accessed
	 * meta-data in-core longer.
	 */
	xfs_buf_set_ref(bp, XFS_INO_REF);

	/*
	 * Use xfs_trans_brelse() to release the buffer containing the on-disk
	 * inode, because it was acquired with xfs_trans_read_buf() in
	 * xfs_imap_to_bp() above.  If tp is NULL, this is just a normal
	 * brelse().  If we're within a transaction, then xfs_trans_brelse()
	 * will only release the buffer if it is not dirty within the
	 * transaction.  It will be OK to release the buffer in this case,
	 * because inodes on disk are never destroyed and we will be locking the
	 * new in-core inode before putting it in the cache where other
	 * processes can find it.  Thus we don't have to worry about the inode
	 * being changed just because we released the buffer.
	 */
 out_brelse:
	xfs_trans_brelse(tp, bp);
	return error;
}