diff options
Diffstat (limited to 'fs/cramfs')
| -rw-r--r-- | fs/cramfs/README | 26 | ||||
| -rw-r--r-- | fs/cramfs/inode.c | 32 |
2 files changed, 29 insertions, 29 deletions
diff --git a/fs/cramfs/README b/fs/cramfs/README index 445d1c2d7646..9d4e7ea311f4 100644 --- a/fs/cramfs/README +++ b/fs/cramfs/README @@ -86,26 +86,26 @@ Block Size (Block size in cramfs refers to the size of input data that is compressed at a time. It's intended to be somewhere around -PAGE_CACHE_SIZE for cramfs_readpage's convenience.) +PAGE_SIZE for cramfs_readpage's convenience.) The superblock ought to indicate the block size that the fs was written for, since comments in <linux/pagemap.h> indicate that -PAGE_CACHE_SIZE may grow in future (if I interpret the comment +PAGE_SIZE may grow in future (if I interpret the comment correctly). -Currently, mkcramfs #define's PAGE_CACHE_SIZE as 4096 and uses that -for blksize, whereas Linux-2.3.39 uses its PAGE_CACHE_SIZE, which in +Currently, mkcramfs #define's PAGE_SIZE as 4096 and uses that +for blksize, whereas Linux-2.3.39 uses its PAGE_SIZE, which in turn is defined as PAGE_SIZE (which can be as large as 32KB on arm). This discrepancy is a bug, though it's not clear which should be changed. -One option is to change mkcramfs to take its PAGE_CACHE_SIZE from +One option is to change mkcramfs to take its PAGE_SIZE from <asm/page.h>. Personally I don't like this option, but it does require the least amount of change: just change `#define -PAGE_CACHE_SIZE (4096)' to `#include <asm/page.h>'. The disadvantage +PAGE_SIZE (4096)' to `#include <asm/page.h>'. The disadvantage is that the generated cramfs cannot always be shared between different kernels, not even necessarily kernels of the same architecture if -PAGE_CACHE_SIZE is subject to change between kernel versions +PAGE_SIZE is subject to change between kernel versions (currently possible with arm and ia64). The remaining options try to make cramfs more sharable. @@ -126,22 +126,22 @@ size. The options are: 1. Always 4096 bytes. 2. Writer chooses blocksize; kernel adapts but rejects blocksize > - PAGE_CACHE_SIZE. + PAGE_SIZE. 3. Writer chooses blocksize; kernel adapts even to blocksize > - PAGE_CACHE_SIZE. + PAGE_SIZE. It's easy enough to change the kernel to use a smaller value than -PAGE_CACHE_SIZE: just make cramfs_readpage read multiple blocks. +PAGE_SIZE: just make cramfs_readpage read multiple blocks. -The cost of option 1 is that kernels with a larger PAGE_CACHE_SIZE +The cost of option 1 is that kernels with a larger PAGE_SIZE value don't get as good compression as they can. The cost of option 2 relative to option 1 is that the code uses variables instead of #define'd constants. The gain is that people -with kernels having larger PAGE_CACHE_SIZE can make use of that if +with kernels having larger PAGE_SIZE can make use of that if they don't mind their cramfs being inaccessible to kernels with -smaller PAGE_CACHE_SIZE values. +smaller PAGE_SIZE values. Option 3 is easy to implement if we don't mind being CPU-inefficient: e.g. get readpage to decompress to a buffer of size MAX_BLKSIZE (which diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index b862bc219cd7..3a32ddf98095 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -137,7 +137,7 @@ static struct inode *get_cramfs_inode(struct super_block *sb, * page cache and dentry tree anyway.. * * This also acts as a way to guarantee contiguous areas of up to - * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to + * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to * worry about end-of-buffer issues even when decompressing a full * page cache. */ @@ -152,7 +152,7 @@ static struct inode *get_cramfs_inode(struct super_block *sb, */ #define BLKS_PER_BUF_SHIFT (2) #define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT) -#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE) +#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE) static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE]; static unsigned buffer_blocknr[READ_BUFFERS]; @@ -173,8 +173,8 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i if (!len) return NULL; - blocknr = offset >> PAGE_CACHE_SHIFT; - offset &= PAGE_CACHE_SIZE - 1; + blocknr = offset >> PAGE_SHIFT; + offset &= PAGE_SIZE - 1; /* Check if an existing buffer already has the data.. */ for (i = 0; i < READ_BUFFERS; i++) { @@ -184,14 +184,14 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i continue; if (blocknr < buffer_blocknr[i]) continue; - blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT; + blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; blk_offset += offset; if (blk_offset + len > BUFFER_SIZE) continue; return read_buffers[i] + blk_offset; } - devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT; + devsize = mapping->host->i_size >> PAGE_SHIFT; /* Ok, read in BLKS_PER_BUF pages completely first. */ for (i = 0; i < BLKS_PER_BUF; i++) { @@ -213,7 +213,7 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i wait_on_page_locked(page); if (!PageUptodate(page)) { /* asynchronous error */ - page_cache_release(page); + put_page(page); pages[i] = NULL; } } @@ -229,12 +229,12 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i struct page *page = pages[i]; if (page) { - memcpy(data, kmap(page), PAGE_CACHE_SIZE); + memcpy(data, kmap(page), PAGE_SIZE); kunmap(page); - page_cache_release(page); + put_page(page); } else - memset(data, 0, PAGE_CACHE_SIZE); - data += PAGE_CACHE_SIZE; + memset(data, 0, PAGE_SIZE); + data += PAGE_SIZE; } return read_buffers[buffer] + offset; } @@ -353,7 +353,7 @@ static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf) u64 id = huge_encode_dev(sb->s_bdev->bd_dev); buf->f_type = CRAMFS_MAGIC; - buf->f_bsize = PAGE_CACHE_SIZE; + buf->f_bsize = PAGE_SIZE; buf->f_blocks = CRAMFS_SB(sb)->blocks; buf->f_bfree = 0; buf->f_bavail = 0; @@ -496,7 +496,7 @@ static int cramfs_readpage(struct file *file, struct page *page) int bytes_filled; void *pgdata; - maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; bytes_filled = 0; pgdata = kmap(page); @@ -516,14 +516,14 @@ static int cramfs_readpage(struct file *file, struct page *page) if (compr_len == 0) ; /* hole */ - else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) { + else if (unlikely(compr_len > (PAGE_SIZE << 1))) { pr_err("bad compressed blocksize %u\n", compr_len); goto err; } else { mutex_lock(&read_mutex); bytes_filled = cramfs_uncompress_block(pgdata, - PAGE_CACHE_SIZE, + PAGE_SIZE, cramfs_read(sb, start_offset, compr_len), compr_len); mutex_unlock(&read_mutex); @@ -532,7 +532,7 @@ static int cramfs_readpage(struct file *file, struct page *page) } } - memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled); + memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled); flush_dcache_page(page); kunmap(page); SetPageUptodate(page); |