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fa0d7e3de6
RCU free the struct inode. This will allow: - Subsequent store-free path walking patch. The inode must be consulted for permissions when walking, so an RCU inode reference is a must. - sb_inode_list_lock to be moved inside i_lock because sb list walkers who want to take i_lock no longer need to take sb_inode_list_lock to walk the list in the first place. This will simplify and optimize locking. - Could remove some nested trylock loops in dcache code - Could potentially simplify things a bit in VM land. Do not need to take the page lock to follow page->mapping. The downsides of this is the performance cost of using RCU. In a simple creat/unlink microbenchmark, performance drops by about 10% due to inability to reuse cache-hot slab objects. As iterations increase and RCU freeing starts kicking over, this increases to about 20%. In cases where inode lifetimes are longer (ie. many inodes may be allocated during the average life span of a single inode), a lot of this cache reuse is not applicable, so the regression caused by this patch is smaller. The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU, however this adds some complexity to list walking and store-free path walking, so I prefer to implement this at a later date, if it is shown to be a win in real situations. I haven't found a regression in any non-micro benchmark so I doubt it will be a problem. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
506 lines
13 KiB
C
506 lines
13 KiB
C
/*
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* QNX4 file system, Linux implementation.
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*
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* Version : 0.2.1
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*
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* Using parts of the xiafs filesystem.
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*
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* History :
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*
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* 01-06-1998 by Richard Frowijn : first release.
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* 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
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* 30-06-1998 by Frank Denis : first step to write inodes.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/highuid.h>
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#include <linux/pagemap.h>
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#include <linux/buffer_head.h>
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#include <linux/writeback.h>
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#include <linux/statfs.h>
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#include "qnx4.h"
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#define QNX4_VERSION 4
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#define QNX4_BMNAME ".bitmap"
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static const struct super_operations qnx4_sops;
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static void qnx4_put_super(struct super_block *sb);
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static struct inode *qnx4_alloc_inode(struct super_block *sb);
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static void qnx4_destroy_inode(struct inode *inode);
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static int qnx4_remount(struct super_block *sb, int *flags, char *data);
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static int qnx4_statfs(struct dentry *, struct kstatfs *);
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static const struct super_operations qnx4_sops =
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{
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.alloc_inode = qnx4_alloc_inode,
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.destroy_inode = qnx4_destroy_inode,
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.put_super = qnx4_put_super,
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.statfs = qnx4_statfs,
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.remount_fs = qnx4_remount,
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};
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static int qnx4_remount(struct super_block *sb, int *flags, char *data)
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{
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struct qnx4_sb_info *qs;
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qs = qnx4_sb(sb);
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qs->Version = QNX4_VERSION;
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*flags |= MS_RDONLY;
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return 0;
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}
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static struct buffer_head *qnx4_getblk(struct inode *inode, int nr,
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int create)
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{
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struct buffer_head *result = NULL;
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if ( nr >= 0 )
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nr = qnx4_block_map( inode, nr );
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if (nr) {
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result = sb_getblk(inode->i_sb, nr);
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return result;
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}
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return NULL;
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}
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struct buffer_head *qnx4_bread(struct inode *inode, int block, int create)
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{
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struct buffer_head *bh;
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bh = qnx4_getblk(inode, block, create);
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if (!bh || buffer_uptodate(bh)) {
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return bh;
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}
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ll_rw_block(READ, 1, &bh);
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wait_on_buffer(bh);
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if (buffer_uptodate(bh)) {
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return bh;
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}
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brelse(bh);
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return NULL;
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}
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static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_head *bh, int create )
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{
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unsigned long phys;
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QNX4DEBUG((KERN_INFO "qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));
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phys = qnx4_block_map( inode, iblock );
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if ( phys ) {
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// logical block is before EOF
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map_bh(bh, inode->i_sb, phys);
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}
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return 0;
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}
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unsigned long qnx4_block_map( struct inode *inode, long iblock )
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{
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int ix;
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long offset, i_xblk;
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unsigned long block = 0;
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struct buffer_head *bh = NULL;
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struct qnx4_xblk *xblk = NULL;
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struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
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u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);
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if ( iblock < le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size) ) {
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// iblock is in the first extent. This is easy.
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block = le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_blk) + iblock - 1;
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} else {
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// iblock is beyond first extent. We have to follow the extent chain.
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i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
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offset = iblock - le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size);
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ix = 0;
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while ( --nxtnt > 0 ) {
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if ( ix == 0 ) {
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// read next xtnt block.
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bh = sb_bread(inode->i_sb, i_xblk - 1);
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if ( !bh ) {
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QNX4DEBUG((KERN_ERR "qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
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return -EIO;
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}
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xblk = (struct qnx4_xblk*)bh->b_data;
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if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
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QNX4DEBUG((KERN_ERR "qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
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return -EIO;
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}
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}
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if ( offset < le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size) ) {
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// got it!
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block = le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_blk) + offset - 1;
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break;
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}
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offset -= le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size);
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if ( ++ix >= xblk->xblk_num_xtnts ) {
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i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
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ix = 0;
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brelse( bh );
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bh = NULL;
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}
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}
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if ( bh )
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brelse( bh );
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}
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QNX4DEBUG((KERN_INFO "qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
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return block;
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}
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static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
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{
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struct super_block *sb = dentry->d_sb;
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u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
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buf->f_type = sb->s_magic;
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buf->f_bsize = sb->s_blocksize;
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buf->f_blocks = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
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buf->f_bfree = qnx4_count_free_blocks(sb);
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buf->f_bavail = buf->f_bfree;
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buf->f_namelen = QNX4_NAME_MAX;
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buf->f_fsid.val[0] = (u32)id;
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buf->f_fsid.val[1] = (u32)(id >> 32);
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return 0;
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}
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/*
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* Check the root directory of the filesystem to make sure
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* it really _is_ a qnx4 filesystem, and to check the size
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* of the directory entry.
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*/
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static const char *qnx4_checkroot(struct super_block *sb)
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{
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struct buffer_head *bh;
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struct qnx4_inode_entry *rootdir;
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int rd, rl;
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int i, j;
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int found = 0;
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if (*(qnx4_sb(sb)->sb->RootDir.di_fname) != '/') {
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return "no qnx4 filesystem (no root dir).";
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} else {
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QNX4DEBUG((KERN_NOTICE "QNX4 filesystem found on dev %s.\n", sb->s_id));
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rd = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_blk) - 1;
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rl = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_size);
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for (j = 0; j < rl; j++) {
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bh = sb_bread(sb, rd + j); /* root dir, first block */
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if (bh == NULL) {
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return "unable to read root entry.";
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}
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for (i = 0; i < QNX4_INODES_PER_BLOCK; i++) {
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rootdir = (struct qnx4_inode_entry *) (bh->b_data + i * QNX4_DIR_ENTRY_SIZE);
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if (rootdir->di_fname != NULL) {
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QNX4DEBUG((KERN_INFO "rootdir entry found : [%s]\n", rootdir->di_fname));
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if (!strcmp(rootdir->di_fname,
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QNX4_BMNAME)) {
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found = 1;
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qnx4_sb(sb)->BitMap = kmalloc( sizeof( struct qnx4_inode_entry ), GFP_KERNEL );
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if (!qnx4_sb(sb)->BitMap) {
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brelse (bh);
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return "not enough memory for bitmap inode";
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}
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memcpy( qnx4_sb(sb)->BitMap, rootdir, sizeof( struct qnx4_inode_entry ) ); /* keep bitmap inode known */
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break;
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}
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}
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}
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brelse(bh);
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if (found != 0) {
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break;
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}
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}
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if (found == 0) {
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return "bitmap file not found.";
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}
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}
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return NULL;
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}
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static int qnx4_fill_super(struct super_block *s, void *data, int silent)
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{
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struct buffer_head *bh;
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struct inode *root;
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const char *errmsg;
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struct qnx4_sb_info *qs;
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int ret = -EINVAL;
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qs = kzalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
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if (!qs)
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return -ENOMEM;
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s->s_fs_info = qs;
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sb_set_blocksize(s, QNX4_BLOCK_SIZE);
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/* Check the superblock signature. Since the qnx4 code is
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dangerous, we should leave as quickly as possible
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if we don't belong here... */
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bh = sb_bread(s, 1);
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if (!bh) {
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printk(KERN_ERR "qnx4: unable to read the superblock\n");
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goto outnobh;
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}
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if ( le32_to_cpup((__le32*) bh->b_data) != QNX4_SUPER_MAGIC ) {
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if (!silent)
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printk(KERN_ERR "qnx4: wrong fsid in superblock.\n");
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goto out;
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}
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s->s_op = &qnx4_sops;
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s->s_magic = QNX4_SUPER_MAGIC;
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s->s_flags |= MS_RDONLY; /* Yup, read-only yet */
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qnx4_sb(s)->sb_buf = bh;
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qnx4_sb(s)->sb = (struct qnx4_super_block *) bh->b_data;
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/* check before allocating dentries, inodes, .. */
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errmsg = qnx4_checkroot(s);
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if (errmsg != NULL) {
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if (!silent)
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printk(KERN_ERR "qnx4: %s\n", errmsg);
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goto out;
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}
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/* does root not have inode number QNX4_ROOT_INO ?? */
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root = qnx4_iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
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if (IS_ERR(root)) {
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printk(KERN_ERR "qnx4: get inode failed\n");
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ret = PTR_ERR(root);
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goto out;
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}
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ret = -ENOMEM;
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s->s_root = d_alloc_root(root);
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if (s->s_root == NULL)
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goto outi;
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brelse(bh);
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return 0;
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outi:
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iput(root);
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out:
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brelse(bh);
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outnobh:
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kfree(qs);
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s->s_fs_info = NULL;
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return ret;
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}
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static void qnx4_put_super(struct super_block *sb)
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{
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struct qnx4_sb_info *qs = qnx4_sb(sb);
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kfree( qs->BitMap );
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kfree( qs );
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sb->s_fs_info = NULL;
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return;
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}
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static int qnx4_writepage(struct page *page, struct writeback_control *wbc)
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{
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return block_write_full_page(page,qnx4_get_block, wbc);
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}
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static int qnx4_readpage(struct file *file, struct page *page)
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{
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return block_read_full_page(page,qnx4_get_block);
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}
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static int qnx4_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata)
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{
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struct qnx4_inode_info *qnx4_inode = qnx4_i(mapping->host);
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int ret;
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*pagep = NULL;
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ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
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qnx4_get_block,
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&qnx4_inode->mmu_private);
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if (unlikely(ret)) {
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loff_t isize = mapping->host->i_size;
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if (pos + len > isize)
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vmtruncate(mapping->host, isize);
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}
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return ret;
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}
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static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
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{
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return generic_block_bmap(mapping,block,qnx4_get_block);
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}
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static const struct address_space_operations qnx4_aops = {
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.readpage = qnx4_readpage,
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.writepage = qnx4_writepage,
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.sync_page = block_sync_page,
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.write_begin = qnx4_write_begin,
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.write_end = generic_write_end,
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.bmap = qnx4_bmap
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};
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struct inode *qnx4_iget(struct super_block *sb, unsigned long ino)
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{
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struct buffer_head *bh;
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struct qnx4_inode_entry *raw_inode;
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int block;
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struct qnx4_inode_entry *qnx4_inode;
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struct inode *inode;
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inode = iget_locked(sb, ino);
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if (!inode)
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return ERR_PTR(-ENOMEM);
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if (!(inode->i_state & I_NEW))
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return inode;
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qnx4_inode = qnx4_raw_inode(inode);
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inode->i_mode = 0;
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QNX4DEBUG((KERN_INFO "reading inode : [%d]\n", ino));
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if (!ino) {
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printk(KERN_ERR "qnx4: bad inode number on dev %s: %lu is "
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"out of range\n",
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sb->s_id, ino);
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iget_failed(inode);
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return ERR_PTR(-EIO);
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}
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block = ino / QNX4_INODES_PER_BLOCK;
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if (!(bh = sb_bread(sb, block))) {
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printk(KERN_ERR "qnx4: major problem: unable to read inode from dev "
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"%s\n", sb->s_id);
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iget_failed(inode);
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return ERR_PTR(-EIO);
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}
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raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
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(ino % QNX4_INODES_PER_BLOCK);
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inode->i_mode = le16_to_cpu(raw_inode->di_mode);
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inode->i_uid = (uid_t)le16_to_cpu(raw_inode->di_uid);
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inode->i_gid = (gid_t)le16_to_cpu(raw_inode->di_gid);
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inode->i_nlink = le16_to_cpu(raw_inode->di_nlink);
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inode->i_size = le32_to_cpu(raw_inode->di_size);
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inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->di_mtime);
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inode->i_mtime.tv_nsec = 0;
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inode->i_atime.tv_sec = le32_to_cpu(raw_inode->di_atime);
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inode->i_atime.tv_nsec = 0;
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inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->di_ctime);
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inode->i_ctime.tv_nsec = 0;
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inode->i_blocks = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);
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memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
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if (S_ISREG(inode->i_mode)) {
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inode->i_fop = &generic_ro_fops;
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inode->i_mapping->a_ops = &qnx4_aops;
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qnx4_i(inode)->mmu_private = inode->i_size;
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} else if (S_ISDIR(inode->i_mode)) {
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inode->i_op = &qnx4_dir_inode_operations;
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inode->i_fop = &qnx4_dir_operations;
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} else if (S_ISLNK(inode->i_mode)) {
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inode->i_op = &page_symlink_inode_operations;
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inode->i_mapping->a_ops = &qnx4_aops;
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qnx4_i(inode)->mmu_private = inode->i_size;
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} else {
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printk(KERN_ERR "qnx4: bad inode %lu on dev %s\n",
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ino, sb->s_id);
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iget_failed(inode);
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brelse(bh);
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return ERR_PTR(-EIO);
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}
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brelse(bh);
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unlock_new_inode(inode);
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return inode;
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}
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static struct kmem_cache *qnx4_inode_cachep;
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static struct inode *qnx4_alloc_inode(struct super_block *sb)
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{
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struct qnx4_inode_info *ei;
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ei = kmem_cache_alloc(qnx4_inode_cachep, GFP_KERNEL);
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if (!ei)
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return NULL;
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return &ei->vfs_inode;
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}
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static void qnx4_i_callback(struct rcu_head *head)
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{
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struct inode *inode = container_of(head, struct inode, i_rcu);
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INIT_LIST_HEAD(&inode->i_dentry);
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kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
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}
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static void qnx4_destroy_inode(struct inode *inode)
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{
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call_rcu(&inode->i_rcu, qnx4_i_callback);
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}
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static void init_once(void *foo)
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{
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struct qnx4_inode_info *ei = (struct qnx4_inode_info *) foo;
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inode_init_once(&ei->vfs_inode);
|
|
}
|
|
|
|
static int init_inodecache(void)
|
|
{
|
|
qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
|
|
sizeof(struct qnx4_inode_info),
|
|
0, (SLAB_RECLAIM_ACCOUNT|
|
|
SLAB_MEM_SPREAD),
|
|
init_once);
|
|
if (qnx4_inode_cachep == NULL)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static void destroy_inodecache(void)
|
|
{
|
|
kmem_cache_destroy(qnx4_inode_cachep);
|
|
}
|
|
|
|
static struct dentry *qnx4_mount(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name, void *data)
|
|
{
|
|
return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super);
|
|
}
|
|
|
|
static struct file_system_type qnx4_fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "qnx4",
|
|
.mount = qnx4_mount,
|
|
.kill_sb = kill_block_super,
|
|
.fs_flags = FS_REQUIRES_DEV,
|
|
};
|
|
|
|
static int __init init_qnx4_fs(void)
|
|
{
|
|
int err;
|
|
|
|
err = init_inodecache();
|
|
if (err)
|
|
return err;
|
|
|
|
err = register_filesystem(&qnx4_fs_type);
|
|
if (err) {
|
|
destroy_inodecache();
|
|
return err;
|
|
}
|
|
|
|
printk(KERN_INFO "QNX4 filesystem 0.2.3 registered.\n");
|
|
return 0;
|
|
}
|
|
|
|
static void __exit exit_qnx4_fs(void)
|
|
{
|
|
unregister_filesystem(&qnx4_fs_type);
|
|
destroy_inodecache();
|
|
}
|
|
|
|
module_init(init_qnx4_fs)
|
|
module_exit(exit_qnx4_fs)
|
|
MODULE_LICENSE("GPL");
|
|
|