The patch titled Subject: fat: add nobarrier to workaround the strange behavior of device has been added to the -mm tree. Its filename is fat-add-nobarrier-to-workaround-the-strange-behavior-of-device.patch

This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/fat-add-nobarrier-to-workaround-the... and later at http://ozlabs.org/~akpm/mmotm/broken-out/fat-add-nobarrier-to-workaround-the...

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------------------------------------------------------ From: OGAWA Hirofumi hirofumi@mail.parknet.co.jp Subject: fat: add nobarrier to workaround the strange behavior of device

There was a report of strange behavior of device with recent blkdev_issue_flush() position change.

The following is simplified usbmon trace:

4203 9.160230 host -> 1.25.1 USBMS 95 SCSI: Synchronize Cache(10) LUN: 0x00 (LBA: 0x00000000, Len: 0) 4206 9.164911 1.25.1 -> host USBMS 77 SCSI: Response LUN: 0x00 (Synchronize Cache(10)) (Good) 4207 9.323927 host -> 1.25.1 USBMS 95 SCSI: Read(10) LUN: 0x00 (LBA: 0x00279950, Len: 240) 4212 9.327138 1.25.1 -> host USBMS 77 SCSI: Response LUN: 0x00 (Read(10)) (Good)

[...]

7323 10.202167 host -> 1.25.1 USBMS 95 SCSI: Synchronize Cache(10) LUN: 0x00 (LBA: 0x00000000, Len: 0) 7326 10.432266 1.25.1 -> host USBMS 77 SCSI: Response LUN: 0x00 (Synchronize Cache(10)) (Good) 7327 10.769092 host -> 1.25.1 USBMS 95 SCSI: Test Unit Ready LUN: 0x00 7330 10.769192 1.25.1 -> host USBMS 77 SCSI: Response LUN: 0x00 (Test Unit Ready) (Good) 7335 12.849093 host -> 1.25.1 USBMS 95 SCSI: Test Unit Ready LUN: 0x00 7338 12.849206 1.25.1 -> host USBMS 77 SCSI: Response LUN: 0x00 (Test Unit Ready) (Check Condition) 7339 12.849209 host -> 1.25.1 USBMS 95 SCSI: Request Sense LUN: 0x00

If "Synchronize Cache" command issued then there is idle time, the device stop to process further commands, and behave as like no media. (it returns NOT_READY [MEDIUM NOT PRESENT] for SENSE command, and this happened on Kindle) [just a guess, the device is trying to detect the "safe-unplug" operation of Windows or such?]

To work around those devices and provide flexibility, this adds "barrier"/"nobarrier" mount options to fat driver.

Link: http://lkml.kernel.org/r/87woh5pyqh.fsf@mail.parknet.co.jp Signed-off-by: OGAWA Hirofumi hirofumi@mail.parknet.co.jp Cc: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/fat/fat.h | 1 + fs/fat/file.c | 8 ++++++-- fs/fat/inode.c | 22 +++++++++++++++++----- 3 files changed, 24 insertions(+), 7 deletions(-)

--- a/fs/fat/fat.h~fat-add-nobarrier-to-workaround-the-strange-behavior-of-device +++ a/fs/fat/fat.h @@ -51,6 +51,7 @@ struct fat_mount_options { tz_set:1, /* Filesystem timestamps' offset set */ rodir:1, /* allow ATTR_RO for directory */ discard:1, /* Issue discard requests on deletions */ + barrier:1, /* Issue FLUSH command */ dos1xfloppy:1; /* Assume default BPB for DOS 1.x floppies */ };

--- a/fs/fat/file.c~fat-add-nobarrier-to-workaround-the-strange-behavior-of-device +++ a/fs/fat/file.c @@ -194,17 +194,21 @@ static int fat_file_release(struct inode int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync) { struct inode *inode = filp->f_mapping->host; + struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); int err;

err = __generic_file_fsync(filp, start, end, datasync); if (err) return err;

- err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping); + err = sync_mapping_buffers(sbi->fat_inode->i_mapping); if (err) return err;

- return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); + if (sbi->options.barrier) + err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); + + return err; }

--- a/fs/fat/inode.c~fat-add-nobarrier-to-workaround-the-strange-behavior-of-device +++ a/fs/fat/inode.c @@ -1011,6 +1011,8 @@ static int fat_show_options(struct seq_f seq_puts(m, ",nfs=stale_rw"); if (opts->discard) seq_puts(m, ",discard"); + if (!opts->barrier) + seq_puts(m, ",nobarrier"); if (opts->dos1xfloppy) seq_puts(m, ",dos1xfloppy");

@@ -1026,8 +1028,9 @@ 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_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont, - Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset, - Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy, + Opt_err_panic, Opt_err_ro, Opt_discard, Opt_barrier, Opt_nobarrier, + Opt_nfs, Opt_time_offset, Opt_nfs_stale_rw, Opt_nfs_nostale_ro, + Opt_err, Opt_dos1xfloppy, };

static const match_table_t fat_tokens = { @@ -1057,6 +1060,8 @@ static const match_table_t fat_tokens = {Opt_err_panic, "errors=panic"}, {Opt_err_ro, "errors=remount-ro"}, {Opt_discard, "discard"}, + {Opt_barrier, "barrier"}, + {Opt_nobarrier, "nobarrier"}, {Opt_nfs_stale_rw, "nfs"}, {Opt_nfs_stale_rw, "nfs=stale_rw"}, {Opt_nfs_nostale_ro, "nfs=nostale_ro"}, @@ -1141,6 +1146,7 @@ static int parse_options(struct super_bl opts->numtail = 1; opts->usefree = opts->nocase = 0; opts->tz_set = 0; + opts->barrier = 1; opts->nfs = 0; opts->errors = FAT_ERRORS_RO; *debug = 0; @@ -1264,6 +1270,15 @@ static int parse_options(struct super_bl case Opt_err_ro: opts->errors = FAT_ERRORS_RO; break; + case Opt_discard: + opts->discard = 1; + break; + case Opt_barrier: + opts->barrier = 1; + break; + case Opt_nobarrier: + opts->barrier = 0; + break; case Opt_nfs_stale_rw: opts->nfs = FAT_NFS_STALE_RW; break; @@ -1327,9 +1342,6 @@ static int parse_options(struct super_bl case Opt_rodir: opts->rodir = 1; break; - case Opt_discard: - opts->discard = 1; - break;

/* obsolete mount options */ case Opt_obsolete: _

Patches currently in -mm which might be from hirofumi@mail.parknet.co.jp are

fat-add-nobarrier-to-workaround-the-strange-behavior-of-device.patch