Messages in this thread Patch in this message |  | | | From | Gordon Oliver <> | | Subject | [2.0.30] ext2 write cleanup/speedup | | Date | Wed, 6 Aug 1997 10:15:33 -0400 (CST) |
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Hi all.
This patch cleans up the code int ext2_write. Under heavy use, the time spent in that function is reduced by about 5%, and besides, it is easier to read. The patch does _not_ change any behaviour. It moves a whole parcel of checks outside of the loop to the beginning of the function.
one interesting note... The check for EFBIG is only triggered if a seek is done, as ext2_get_blk fails at size = 0x7ffffc00 (2G - block size I presume) This code has been running on my system without problems for about 3 months... -------------------------------------------------------------------- diff --recursive -u --new-file linux-2.0.30/fs/ext2/file.c work/fs/ext2/file.c --- linux-2.0.30/fs/ext2/file.c Tue Feb 20 05:28:13 1996 +++ work/fs/ext2/file.c Mon Apr 28 14:25:39 1997 @@ -80,42 +80,63 @@ NULL /* smap */ }; +static int ext2_sync_write(int buffercount, struct buffer_head *bufferlist[]) +{ + int i; + int write_error; + + write_error = 0; + ll_rw_block(WRITE, buffercount, bufferlist); + wait_on_buffer(bufferlist[buffercount-1]); + for(i=0; i<buffercount; i++){ + wait_on_buffer(bufferlist[i]); + if (!buffer_uptodate(bufferlist[i])) + write_error=1; + brelse(bufferlist[i]); + } + return write_error; +} + +/* + * known bugs (from looking at the code) + * 1) count is treated as signed, and should be unsigned. + * 2) disk write error results in incorrect size passed back on + * O_SYNC files. + * 3) inodes are not written back at the end of the O_SYNC write. + */ static int ext2_file_write (struct inode * inode, struct file * filp, const char * buf, int count) { const loff_t two_gb = 2147483647; loff_t pos; - off_t pos2; long block; int offset; int written, c; struct buffer_head * bh, *bufferlist[NBUF]; struct super_block * sb; int err; - int i,buffercount,write_error; + int buffercount; - write_error = buffercount = 0; - if (!inode) { - printk("ext2_file_write: inode = NULL\n"); - return -EINVAL; - } + buffercount = 0; + written = 0; + if (!inode) + goto bad_inode; sb = inode->i_sb; if (sb->s_flags & MS_RDONLY) - /* - * This fs has been automatically remounted ro because of errors - */ - return -ENOSPC; - - if (!S_ISREG(inode->i_mode)) { - ext2_warning (sb, "ext2_file_write", "mode = %07o", - inode->i_mode); - return -EINVAL; - } + goto ro_fs; + + if (!S_ISREG(inode->i_mode)) + goto bad_mode; if (filp->f_flags & O_APPEND) pos = inode->i_size; else pos = filp->f_pos; - pos2 = (off_t) pos; + if (count <= 0) /* broken? */ + goto exit; + if (pos >= two_gb) + goto big_file; + if (two_gb - pos < count) + count = two_gb - pos; /* * If a file has been opened in synchronous mode, we have to ensure * that meta-data will also be written synchronously. Thus, we @@ -124,22 +145,13 @@ */ if (filp->f_flags & O_SYNC) inode->u.ext2_i.i_osync++; - block = pos2 >> EXT2_BLOCK_SIZE_BITS(sb); - offset = pos2 & (sb->s_blocksize - 1); + block = ((off_t)pos) >> EXT2_BLOCK_SIZE_BITS(sb); + offset = ((off_t)pos) & (sb->s_blocksize - 1); c = sb->s_blocksize - offset; - written = 0; while (count > 0) { - if (pos > two_gb) { - if (!written) - written = -EFBIG; - break; - } bh = ext2_getblk (inode, block, 1, &err); - if (!bh) { - if (!written) - written = err; - break; - } + if (!bh) + goto no_block; count -= c; if (count < 0) c += count; @@ -155,49 +167,66 @@ } memcpy_fromfs (bh->b_data + offset, buf, c); update_vm_cache(inode, pos, bh->b_data + offset, c); - pos2 += c; + mark_buffer_uptodate(bh, 1); + mark_buffer_dirty(bh, 0); pos += c; written += c; buf += c; - mark_buffer_uptodate(bh, 1); - mark_buffer_dirty(bh, 0); - if (filp->f_flags & O_SYNC) - bufferlist[buffercount++] = bh; - else - brelse(bh); - if (buffercount == NBUF){ - ll_rw_block(WRITE, buffercount, bufferlist); - for(i=0; i<buffercount; i++){ - wait_on_buffer(bufferlist[i]); - if (!buffer_uptodate(bufferlist[i])) - write_error=1; - brelse(bufferlist[i]); - } - buffercount=0; - } - if(write_error) - break; block++; offset = 0; c = sb->s_blocksize; - } - if ( buffercount ){ - ll_rw_block(WRITE, buffercount, bufferlist); - for(i=0; i<buffercount; i++){ - wait_on_buffer(bufferlist[i]); - if (!buffer_uptodate(bufferlist[i])) - write_error=1; - brelse(bufferlist[i]); + if (!(filp->f_flags & O_SYNC)) { + brelse(bh); + continue; } - } - if (pos > inode->i_size) - inode->i_size = pos; + else { + bufferlist[buffercount++] = bh; + if (buffercount == NBUF) { + int tmp = buffercount; + + buffercount = 0; + if (ext2_sync_write(tmp, bufferlist)) + break; + } + } + } +clean_and_exit: if (filp->f_flags & O_SYNC) + { + if ( buffercount ) + ext2_sync_write(buffercount, bufferlist); inode->u.ext2_i.i_osync--; + } + if (pos > inode->i_size) + inode->i_size = pos; inode->i_ctime = inode->i_mtime = CURRENT_TIME; filp->f_pos = pos; inode->i_dirt = 1; +exit: return written; + +no_block: + if (!written) + written = err; + goto clean_and_exit; + +bad_inode: + printk("ext2_file_write: inode = NULL\n"); + return -EINVAL; + +bad_mode: + ext2_warning (sb, "ext2_file_write", "mode = %07o", + inode->i_mode); + return -EINVAL; + +big_file: + return -EFBIG; + +ro_fs: + /* + * This fs has been automatically remounted ro because of errors + */ + return -ENOSPC; } /*
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