From: Holden Karau <[email protected]> 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 <[email protected]>
---
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);
-
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