From: Holden Karau <holden@xxxxxxxxxxxxx> http://www.holdenkarau.com This is an attempt at improving fat_mirror_bhs in sync mode [namely it writes all of the data for a backup block, and then blocks untill finished]. The old behavior would write & block in smaller chunks, so this should be slightly faster. It also removes the fix me requesting that it be fixed to behave this way :-) Signed-off-by: Holden Karau <holden@xxxxxxxxxxxxx> --- This is an improved version of an earlier patch, I've cleaned up the formatting, it now also groups the write for the primary fat block [so even if the user has only 2 FATs it should still be slightly faster]. and it now handles running running out of memory more gracefully. If no one objects, I'd like to see if it would be possible to put this in the -mm tree to make sure it doesn't eat anyones fs :-) In case the patch gets mangled, I've put it up at http://www.holdenkarau.com/~holden/projects/fat/001_improve_fat_sync_performance_revised4.patch And now for the patch: --- a/fs/fat/fatent.c 2006-09-19 23:42:06.000000000 -0400 +++ b/fs/fat/fatent.c 2006-11-01 10:58:19.000000000 -0500 @@ -1,5 +1,6 @@ /* * Copyright (C) 2004, OGAWA Hirofumi + * Copyright (C) 2006, Holden Karau [Xandros] * Released under GPL v2. */ @@ -343,52 +344,83 @@ int fat_ent_read(struct inode *inode, st return ops->ent_get(fatent); } -/* FIXME: We can write the blocks as more big chunk. */ -static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, - int nr_bhs) + + +static int fat_mirror_bhs_optw(struct super_block *sb, struct buffer_head **bhs, + int nr_bhs , int wait) { struct msdos_sb_info *sbi = MSDOS_SB(sb); - struct buffer_head *c_bh; - int err, n, copy; + struct buffer_head **c_bh; + int err, n, copy, i; + /* Always wait if mounted -o sync */ + if (sb->s_flags & MS_SYNCHRONOUS ) + wait = 1; + c_bh = kmalloc(nr_bhs*(sbi->fats) , GFP_KERNEL); + if (NULL == c_bh) { + printk(KERN_CRIT "not enough memory to store pointers to FAT blocks, will not sync. Possible data loss\n"); + err = -ENOMEM; + goto error; + } err = 0; + i = 0; for (copy = 1; copy < sbi->fats; copy++) { sector_t backup_fat = sbi->fat_length * copy; - - for (n = 0; n < nr_bhs; n++) { - c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); - if (!c_bh) { - err = -ENOMEM; - goto error; + for (n = 0 ; n < nr_bhs ; n++ ) { + c_bh[(copy-1)*nr_bhs+n] = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); + /* If there is not enough memory, fall back to the old system */ + if (!c_bh[(copy-1)*nr_bhs+n]) { + printk("fat: not enough memory for all blocks , syncing at %d\n" ,(copy-1)*nr_bhs+n); + fat_sync_bhs_optw( c_bh+i , (copy-1)*nr_bhs+n-i-1 , wait ); + /* Free the now sync'd blocks */ + for (; i < (copy-1)*nr_bhs+n ; i++) + brelse(c_bh[i]); + /* We try the same block again */ + c_bh[(copy-1)*nr_bhs+n] = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); + if (!c_bh[(copy-1)*nr_bhs+n]) { + printk(KERN_CRIT "fat:not enough memory for block after existing blocks released. Possible data loss.\n"); + err = -ENOMEM; + goto error; + } } - memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); - set_buffer_uptodate(c_bh); - mark_buffer_dirty(c_bh); - if (sb->s_flags & MS_SYNCHRONOUS) - err = sync_dirty_buffer(c_bh); - brelse(c_bh); - if (err) - goto error; + memcpy(c_bh[(copy-1)*nr_bhs+n]->b_data, bhs[n]->b_data, sb->s_blocksize); + set_buffer_uptodate(c_bh[(copy-1)*nr_bhs+n]); + mark_buffer_dirty(c_bh[(copy-1)*nr_bhs+n]); } } + + if (wait) { + for (n = 0 ; n < nr_bhs ; n++) + c_bh[nr_bhs*(sbi->fats-1)+n] = bhs[n]; + } + err = fat_sync_bhs_optw( c_bh+i , nr_bhs*(sbi->fats+wait-1)-i , wait ); + if (err) + goto error; + for (n = 0; n+i < nr_bhs*(sbi->fats-1); n++ ) { + brelse(c_bh[n+i]); + } error: + if (NULL != c_bh) { + kfree(c_bh); + } return err; } +static inline int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, + int nr_bhs ) +{ + return fat_mirror_bhs_optw(sb , bhs , nr_bhs, 0); +} + + int fat_ent_write(struct inode *inode, struct fat_entry *fatent, int new, int wait) { struct super_block *sb = inode->i_sb; struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; - int err; ops->ent_put(fatent, new); - if (wait) { - err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); - if (err) - return err; - } - return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); + return fat_mirror_bhs_optw(sb, fatent->bhs, fatent->nr_bhs , wait); } static inline int fat_ent_next(struct msdos_sb_info *sbi, @@ -505,9 +537,9 @@ out: fatent_brelse(&fatent); if (!err) { if (inode_needs_sync(inode)) - err = fat_sync_bhs(bhs, nr_bhs); - if (!err) - err = fat_mirror_bhs(sb, bhs, nr_bhs); + err = fat_mirror_bhs_optw(sb , bhs, nr_bhs , 1); + else + err = fat_mirror_bhs_optw(sb, bhs, nr_bhs , 0 ); } for (i = 0; i < nr_bhs; i++) brelse(bhs[i]); @@ -549,11 +581,6 @@ int fat_free_clusters(struct inode *inod } if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { - if (sb->s_flags & MS_SYNCHRONOUS) { - err = fat_sync_bhs(bhs, nr_bhs); - if (err) - goto error; - } err = fat_mirror_bhs(sb, bhs, nr_bhs); if (err) goto error; @@ -564,11 +591,6 @@ int fat_free_clusters(struct inode *inod fat_collect_bhs(bhs, &nr_bhs, &fatent); } while (cluster != FAT_ENT_EOF); - if (sb->s_flags & MS_SYNCHRONOUS) { - err = fat_sync_bhs(bhs, nr_bhs); - if (err) - goto error; - } err = fat_mirror_bhs(sb, bhs, nr_bhs); error: fatent_brelse(&fatent); --- a/fs/fat/misc.c 2006-09-19 23:42:06.000000000 -0400 +++ b/fs/fat/misc.c 2006-11-01 10:18:08.000000000 -0500 @@ -194,19 +194,28 @@ void fat_date_unix2dos(int unix_date, __ EXPORT_SYMBOL_GPL(fat_date_unix2dos); -int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) + + +int fat_sync_bhs_optw(struct buffer_head **bhs, int nr_bhs ,int wait) { int i, err = 0; ll_rw_block(SWRITE, nr_bhs, bhs); - for (i = 0; i < nr_bhs; i++) { - wait_on_buffer(bhs[i]); - if (buffer_eopnotsupp(bhs[i])) { - clear_buffer_eopnotsupp(bhs[i]); - err = -EOPNOTSUPP; - } else if (!err && !buffer_uptodate(bhs[i])) - err = -EIO; + if (wait) { + for (i = 0; i < nr_bhs; i++) { + wait_on_buffer(bhs[i]); + if (buffer_eopnotsupp(bhs[i])) { + clear_buffer_eopnotsupp(bhs[i]); + err = -EOPNOTSUPP; + } else if (!err && !buffer_uptodate(bhs[i])) + err = -EIO; + } } + return err; } +inline int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs ) { + return fat_sync_bhs_optw(bhs , nr_bhs , 1); +} + --- a/include/linux/msdos_fs.h 2006-09-19 23:42:06.000000000 -0400 +++ b/include/linux/msdos_fs.h 2006-10-25 18:53:50.000000000 -0400 @@ -419,6 +419,7 @@ extern int fat_chain_add(struct inode *i extern int date_dos2unix(unsigned short time, unsigned short date); extern void fat_date_unix2dos(int unix_date, __le16 *time, __le16 *date); extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs); +extern int fat_sync_bhs_optw(struct buffer_head **bhs, int nr_bhs, int wait); int fat_cache_init(void); void fat_cache_destroy(void); - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
