minix/servers/ext2/cache.c

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/* The file system maintains a buffer cache to reduce the number of disk
* accesses needed. Whenever a read or write to the disk is done, a check is
* first made to see if the block is in the cache. This file manages the
* cache.
*
* The entry points into this file are:
* get_block: request to fetch a block for reading or writing from cache
* put_block: return a block previously requested with get_block
* invalidate: remove all the cache blocks on some device
*
* Private functions:
* rw_block: read or write a block from the disk itself
*
* Created (MFS based):
* February 2010 (Evgeniy Ivanov)
*/
#include "fs.h"
#include <minix/u64.h>
#include <minix/bdev.h>
#include <minix/libminixfs.h>
#include <stdlib.h>
#include <assert.h>
#include "buf.h"
#include "super.h"
#include "inode.h"
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static void rm_lru(struct buf *bp);
static void rw_block(struct buf *, int);
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static int vmcache_avail = -1; /* 0 if not available, >0 if available. */
/*===========================================================================*
* get_block *
*===========================================================================*/
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struct buf *get_block(
register dev_t dev, /* on which device is the block? */
register block_t block, /* which block is wanted? */
int only_search /* if NO_READ, don't read, else act normal */
)
{
/* Check to see if the requested block is in the block cache. If so, return
* a pointer to it. If not, evict some other block and fetch it (unless
* 'only_search' is 1). All the blocks in the cache that are not in use
* are linked together in a chain, with 'front' pointing to the least recently
* used block and 'rear' to the most recently used block. If 'only_search' is
* 1, the block being requested will be overwritten in its entirety, so it is
* only necessary to see if it is in the cache; if it is not, any free buffer
* will do. It is not necessary to actually read the block in from disk.
* If 'only_search' is PREFETCH, the block need not be read from the disk,
* and the device is not to be marked on the block, so callers can tell if
* the block returned is valid.
* In addition to the LRU chain, there is also a hash chain to link together
* blocks whose block numbers end with the same bit strings, for fast lookup.
*/
int b;
static struct buf *bp, *prev_ptr;
u64_t yieldid = VM_BLOCKID_NONE, getid = make64(dev, block);
int vmcache = 0;
assert(buf_hash);
assert(buf);
assert(nr_bufs > 0);
if(vmcache_avail < 0) {
/* Test once for the availability of the vm yield block feature. */
if(vm_forgetblock(VM_BLOCKID_NONE) == ENOSYS) {
vmcache_avail = 0;
} else {
vmcache_avail = 1;
}
}
/* use vmcache if it's available, and allowed, and we're not doing
* i/o on a ram disk device.
*/
if(vmcache_avail && may_use_vmcache && major(dev) != MEMORY_MAJOR)
vmcache = 1;
ASSERT(fs_block_size > 0);
/* Search the hash chain for (dev, block). Do_read() can use
* get_block(NO_DEV ...) to get an unnamed block to fill with zeros when
* someone wants to read from a hole in a file, in which case this search
* is skipped
*/
if (dev != NO_DEV) {
b = BUFHASH(block);
bp = buf_hash[b];
while (bp != NULL) {
if (bp->b_blocknr == block && bp->b_dev == dev) {
/* Block needed has been found. */
if (bp->b_count == 0) rm_lru(bp);
bp->b_count++; /* record that block is in use */
ASSERT(bp->b_bytes == fs_block_size);
ASSERT(bp->b_dev == dev);
ASSERT(bp->b_dev != NO_DEV);
ASSERT(bp->bp);
return(bp);
} else {
/* This block is not the one sought. */
bp = bp->b_hash; /* move to next block on hash chain */
}
}
}
/* Desired block is not on available chain. Take oldest block ('front'). */
if ((bp = front) == NULL) panic("all buffers in use", nr_bufs);
if(bp->b_bytes < fs_block_size) {
ASSERT(!bp->bp);
ASSERT(bp->b_bytes == 0);
if(!(bp->bp = alloc_contig( (size_t) fs_block_size, 0, NULL))) {
ext2_debug("ext2: couldn't allocate a new block.\n");
for(bp = front;
bp && bp->b_bytes < fs_block_size; bp = bp->b_next)
;
if(!bp) {
panic("no buffer available");
}
} else {
bp->b_bytes = fs_block_size;
}
}
ASSERT(bp);
ASSERT(bp->bp);
ASSERT(bp->b_bytes == fs_block_size);
ASSERT(bp->b_count == 0);
rm_lru(bp);
/* Remove the block that was just taken from its hash chain. */
b = BUFHASH(bp->b_blocknr);
prev_ptr = buf_hash[b];
if (prev_ptr == bp) {
buf_hash[b] = bp->b_hash;
} else {
/* The block just taken is not on the front of its hash chain. */
while (prev_ptr->b_hash != NULL)
if (prev_ptr->b_hash == bp) {
prev_ptr->b_hash = bp->b_hash; /* found it */
break;
} else {
prev_ptr = prev_ptr->b_hash; /* keep looking */
}
}
/* If the block taken is dirty, make it clean by writing it to the disk.
* Avoid hysteresis by flushing all other dirty blocks for the same device.
*/
if (bp->b_dev != NO_DEV) {
if (bp->b_dirt == DIRTY) flushall(bp->b_dev);
/* Are we throwing out a block that contained something?
* Give it to VM for the second-layer cache.
*/
yieldid = make64(bp->b_dev, bp->b_blocknr);
assert(bp->b_bytes == fs_block_size);
bp->b_dev = NO_DEV;
}
/* Fill in block's parameters and add it to the hash chain where it goes. */
bp->b_dev = dev; /* fill in device number */
bp->b_blocknr = block; /* fill in block number */
bp->b_count++; /* record that block is being used */
b = BUFHASH(bp->b_blocknr);
bp->b_hash = buf_hash[b];
buf_hash[b] = bp; /* add to hash list */
if(dev == NO_DEV) {
if(vmcache && cmp64(yieldid, VM_BLOCKID_NONE) != 0) {
vm_yield_block_get_block(yieldid, VM_BLOCKID_NONE,
bp->bp, fs_block_size);
}
return(bp); /* If the caller wanted a NO_DEV block, work is done. */
}
/* Go get the requested block unless searching or prefetching. */
if(only_search == PREFETCH || only_search == NORMAL) {
/* Block is not found in our cache, but we do want it
* if it's in the vm cache.
*/
if(vmcache) {
/* If we can satisfy the PREFETCH or NORMAL request
* from the vm cache, work is done.
*/
if(vm_yield_block_get_block(yieldid, getid,
bp->bp, fs_block_size) == OK) {
return bp;
}
}
}
if(only_search == PREFETCH) {
/* PREFETCH: don't do i/o. */
bp->b_dev = NO_DEV;
} else if (only_search == NORMAL) {
rw_block(bp, READING);
} else if(only_search == NO_READ) {
/* we want this block, but its contents
* will be overwritten. VM has to forget
* about it.
*/
if(vmcache) {
vm_forgetblock(getid);
}
} else
panic("unexpected only_search value: %d", only_search);
assert(bp->bp);
return(bp); /* return the newly acquired block */
}
/*===========================================================================*
* put_block *
*===========================================================================*/
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void put_block(
register struct buf *bp, /* pointer to the buffer to be released */
int block_type /* INODE_BLOCK, DIRECTORY_BLOCK, or whatever */
)
{
/* Return a block to the list of available blocks. Depending on 'block_type'
* it may be put on the front or rear of the LRU chain. Blocks that are
* expected to be needed again shortly (e.g., partially full data blocks)
* go on the rear; blocks that are unlikely to be needed again shortly
* (e.g., full data blocks) go on the front. Blocks whose loss can hurt
* the integrity of the file system (e.g., inode blocks) are written to
* disk immediately if they are dirty.
*/
if (bp == NULL) return; /* it is easier to check here than in caller */
bp->b_count--; /* there is one use fewer now */
if (bp->b_count != 0) return; /* block is still in use */
bufs_in_use--; /* one fewer block buffers in use */
/* Put this block back on the LRU chain. If the ONE_SHOT bit is set in
* 'block_type', the block is not likely to be needed again shortly, so put
* it on the front of the LRU chain where it will be the first one to be
* taken when a free buffer is needed later.
*/
if (bp->b_dev == DEV_RAM || (block_type & ONE_SHOT)) {
/* Block probably won't be needed quickly. Put it on front of chain.
* It will be the next block to be evicted from the cache.
*/
bp->b_prev = NULL;
bp->b_next = front;
if (front == NULL)
rear = bp; /* LRU chain was empty */
else
front->b_prev = bp;
front = bp;
}
else {
/* Block probably will be needed quickly. Put it on rear of chain.
* It will not be evicted from the cache for a long time.
*/
bp->b_prev = rear;
bp->b_next = NULL;
if (rear == NULL)
front = bp;
else
rear->b_next = bp;
rear = bp;
}
/* Some blocks are so important (e.g., inodes, indirect blocks) that they
* should be written to the disk immediately to avoid messing up the file
* system in the event of a crash.
*/
if ((block_type & WRITE_IMMED) && bp->b_dirt==DIRTY && bp->b_dev != NO_DEV) {
rw_block(bp, WRITING);
}
}
/*===========================================================================*
* rw_block *
*===========================================================================*/
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static void rw_block(
register struct buf *bp, /* buffer pointer */
int rw_flag /* READING or WRITING */
)
{
/* Read or write a disk block. This is the only routine in which actual disk
* I/O is invoked. If an error occurs, a message is printed here, but the error
* is not reported to the caller. If the error occurred while purging a block
* from the cache, it is not clear what the caller could do about it anyway.
*/
int r, op_failed = 0;
u64_t pos;
dev_t dev;
if ( (dev = bp->b_dev) != NO_DEV) {
pos = mul64u(bp->b_blocknr, fs_block_size);
if (rw_flag == READING)
r = bdev_read(dev, pos, bp->b_data, fs_block_size,
BDEV_NOFLAGS);
else
r = bdev_write(dev, pos, bp->b_data, fs_block_size,
BDEV_NOFLAGS);
if (r < 0) {
printf("Ext2(%d) I/O error on device %d/%d, block %u\n",
SELF_E, major(dev), minor(dev), bp->b_blocknr);
op_failed = 1;
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
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} else if (r != (ssize_t) fs_block_size) {
r = END_OF_FILE;
op_failed = 1;
}
if (op_failed) {
bp->b_dev = NO_DEV; /* invalidate block */
/* Report read errors to interested parties. */
if (rw_flag == READING) rdwt_err = r;
}
}
bp->b_dirt = CLEAN;
}
/*===========================================================================*
* invalidate *
*===========================================================================*/
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void invalidate(
dev_t device /* device whose blocks are to be purged */
)
{
/* Remove all the blocks belonging to some device from the cache. */
register struct buf *bp;
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++)
if (bp->b_dev == device) bp->b_dev = NO_DEV;
vm_forgetblocks();
}
/*===========================================================================*
* flushall *
*===========================================================================*/
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void flushall(
dev_t dev /* device to flush */
)
{
/* Flush all dirty blocks for one device. */
register struct buf *bp;
static struct buf **dirty; /* static so it isn't on stack */
static int unsigned dirtylistsize = 0;
int ndirty;
if(dirtylistsize != nr_bufs) {
if(dirtylistsize > 0) {
assert(dirty != NULL);
free(dirty);
}
if(!(dirty = malloc(sizeof(dirty[0])*nr_bufs)))
panic("couldn't allocate dirty buf list");
dirtylistsize = nr_bufs;
}
for (bp = &buf[0], ndirty = 0; bp < &buf[nr_bufs]; bp++)
if (bp->b_dirt == DIRTY && bp->b_dev == dev) dirty[ndirty++] = bp;
rw_scattered(dev, dirty, ndirty, WRITING);
}
/*===========================================================================*
* rw_scattered *
*===========================================================================*/
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void rw_scattered(
dev_t dev, /* major-minor device number */
struct buf **bufq, /* pointer to array of buffers */
int bufqsize, /* number of buffers */
int rw_flag /* READING or WRITING */
)
{
/* Read or write scattered data from a device. */
register struct buf *bp;
int gap;
register int i;
register iovec_t *iop;
static iovec_t *iovec = NULL;
u64_t pos;
int j, r;
STATICINIT(iovec, NR_IOREQS);
/* (Shell) sort buffers on b_blocknr. */
gap = 1;
do
gap = 3 * gap + 1;
while (gap <= bufqsize);
while (gap != 1) {
gap /= 3;
for (j = gap; j < bufqsize; j++) {
for (i = j - gap;
i >= 0 && bufq[i]->b_blocknr > bufq[i + gap]->b_blocknr;
i -= gap) {
bp = bufq[i];
bufq[i] = bufq[i + gap];
bufq[i + gap] = bp;
}
}
}
/* Set up I/O vector and do I/O. The result of dev_io is OK if everything
* went fine, otherwise the error code for the first failed transfer.
*/
while (bufqsize > 0) {
for (j = 0, iop = iovec; j < NR_IOREQS && j < bufqsize; j++, iop++) {
bp = bufq[j];
if (bp->b_blocknr != (block_t) bufq[0]->b_blocknr + j) break;
iop->iov_addr = (vir_bytes) bp->b_data;
iop->iov_size = (vir_bytes) fs_block_size;
}
pos = mul64u(bufq[0]->b_blocknr, fs_block_size);
if (rw_flag == READING)
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
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r = bdev_gather(dev, pos, iovec, j, BDEV_NOFLAGS);
else
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
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r = bdev_scatter(dev, pos, iovec, j, BDEV_NOFLAGS);
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
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/* Harvest the results. The driver may have returned an error, or it
* may have done less than what we asked for.
*/
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
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if (r < 0) {
printf("ext2: I/O error %d on device %d/%d, block %u\n",
r, major(dev), minor(dev), bufq[0]->b_blocknr);
}
for (i = 0; i < j; i++) {
bp = bufq[i];
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
2011-11-22 13:27:53 +01:00
if (r < (ssize_t) fs_block_size) {
/* Transfer failed. */
if (i == 0) {
bp->b_dev = NO_DEV; /* invalidate block */
vm_forgetblocks();
}
break;
}
if (rw_flag == READING) {
bp->b_dev = dev; /* validate block */
put_block(bp, PARTIAL_DATA_BLOCK);
} else {
bp->b_dirt = CLEAN;
}
Split block/character protocols and libdriver This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
2011-11-22 13:27:53 +01:00
r -= fs_block_size;
}
bufq += i;
bufqsize -= i;
if (rw_flag == READING) {
/* Don't bother reading more than the device is willing to
* give at this time. Don't forget to release those extras.
*/
while (bufqsize > 0) {
put_block(*bufq++, PARTIAL_DATA_BLOCK);
bufqsize--;
}
}
if (rw_flag == WRITING && i == 0) {
/* We're not making progress, this means we might keep
* looping. Buffers remain dirty if un-written. Buffers are
* lost if invalidate()d or LRU-removed while dirty. This
* is better than keeping unwritable blocks around forever..
*/
break;
}
}
}
/*===========================================================================*
* rm_lru *
*===========================================================================*/
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static void rm_lru(
struct buf *bp
)
{
/* Remove a block from its LRU chain. */
struct buf *next_ptr, *prev_ptr;
bufs_in_use++;
next_ptr = bp->b_next; /* successor on LRU chain */
prev_ptr = bp->b_prev; /* predecessor on LRU chain */
if (prev_ptr != NULL)
prev_ptr->b_next = next_ptr;
else
front = next_ptr; /* this block was at front of chain */
if (next_ptr != NULL)
next_ptr->b_prev = prev_ptr;
else
rear = prev_ptr; /* this block was at rear of chain */
}
/*===========================================================================*
* set_blocksize *
*===========================================================================*/
2012-03-25 20:25:53 +02:00
void set_blocksize(unsigned int blocksize, u32_t blocks,
u32_t freeblocks, dev_t majordev)
{
struct buf *bp;
struct inode *rip;
int new_nr_bufs;
ASSERT(blocksize > 0);
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++)
if(bp->b_count != 0) panic("change blocksize with buffer in use");
for (rip = &inode[0]; rip < &inode[NR_INODES]; rip++)
if (rip->i_count > 0) panic("change blocksize with inode in use");
new_nr_bufs = fs_bufs_heuristic(10, blocks, freeblocks, blocksize, majordev);
buf_pool(new_nr_bufs);
fs_block_size = blocksize;
}
/*===========================================================================*
* buf_pool *
*===========================================================================*/
2012-03-25 20:25:53 +02:00
void buf_pool(int new_nr_bufs)
{
/* Initialize the buffer pool. */
register struct buf *bp;
assert(new_nr_bufs > 0);
if(nr_bufs > 0) {
assert(buf);
(void) fs_sync();
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) {
if(bp->bp) {
assert(bp->b_bytes > 0);
free_contig(bp->bp, bp->b_bytes);
}
}
}
if(buf)
free(buf);
if(!(buf = calloc(sizeof(buf[0]), new_nr_bufs)))
panic("couldn't allocate buf list (%d)", new_nr_bufs);
if(buf_hash)
free(buf_hash);
if(!(buf_hash = calloc(sizeof(buf_hash[0]), new_nr_bufs)))
panic("couldn't allocate buf hash list (%d)", new_nr_bufs);
nr_bufs = new_nr_bufs;
bufs_in_use = 0;
front = &buf[0];
rear = &buf[nr_bufs - 1];
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) {
bp->b_blocknr = NO_BLOCK;
bp->b_dev = NO_DEV;
bp->b_next = bp + 1;
bp->b_prev = bp - 1;
bp->bp = NULL;
bp->b_bytes = 0;
}
buf[0].b_prev = NULL;
buf[nr_bufs - 1].b_next = NULL;
for (bp = &buf[0]; bp < &buf[nr_bufs]; bp++) bp->b_hash = bp->b_next;
buf_hash[0] = front;
vm_forgetblocks();
}