Currently shipping discard capable SSDs and arrays have rather sub-optimal
implementations of the command and can the use of it can cause massive
slowdowns. Make issueing these commands option as it's already in btrfs
and gfs2.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: linux-2.6/fs/fat/fat.h
===================================================================
--- linux-2.6.orig/fs/fat/fat.h 2009-11-18 13:47:49.380003970 +0100
+++ linux-2.6/fs/fat/fat.h 2009-11-18 13:48:13.169014622 +0100
@@ -44,7 +44,8 @@ struct fat_mount_options {
nocase:1, /* Does this need case conversion? 0=need case conversion*/
usefree:1, /* Use free_clusters for FAT32 */
tz_utc:1, /* Filesystem timestamps are in UTC */
- rodir:1; /* allow ATTR_RO for directory */
+ rodir:1, /* allow ATTR_RO for directory */
+ discard:1; /* Issue discard requests on deletions */
};
#define FAT_HASH_BITS 8
Index: linux-2.6/fs/fat/fatent.c
===================================================================
--- linux-2.6.orig/fs/fat/fatent.c 2009-11-18 13:48:24.102254108 +0100
+++ linux-2.6/fs/fat/fatent.c 2009-11-18 13:49:14.338033708 +0100
@@ -573,8 +573,11 @@ int fat_free_clusters(struct inode *inod
if (cluster != fatent.entry + 1) {
int nr_clus = fatent.entry - first_cl + 1;
- sb_issue_discard(sb, fat_clus_to_blknr(sbi, first_cl),
- nr_clus * sbi->sec_per_clus);
+ if (sbi->options.discard) {
+ sb_issue_discard(sb,
+ fat_clus_to_blknr(sbi, first_cl),
+ nr_clus * sbi->sec_per_clus);
+ }
first_cl = cluster;
}
Index: linux-2.6/fs/fat/inode.c
===================================================================
--- linux-2.6.orig/fs/fat/inode.c 2009-11-18 13:46:40.484256340 +0100
+++ linux-2.6/fs/fat/inode.c 2009-11-18 13:47:39.457256306 +0100
@@ -871,7 +871,7 @@ enum {
Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
- Opt_err_panic, Opt_err_ro, Opt_err,
+ Opt_err_panic, Opt_err_ro, Opt_discard, Opt_err,
};
static const match_table_t fat_tokens = {
@@ -910,6 +910,7 @@ static const match_table_t fat_tokens =
{Opt_obsolate, "cvf_format=%20s"},
{Opt_obsolate, "cvf_options=%100s"},
{Opt_obsolate, "posix"},
+ {Opt_discard, "discard"},
{Opt_err, NULL},
};
static const match_table_t msdos_tokens = {
@@ -1136,6 +1137,9 @@ static int parse_options(char *options,
case Opt_rodir:
opts->rodir = 1;
break;
+ case Opt_discard:
+ opts->discard = 1;
+ break;
/* obsolete mount options */
case Opt_obsolate:
--
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