8bc3be2751
After making dirty a 100M file, the normal behavior is to start the writeback for all data after 30s delays. But sometimes the following happens instead: - after 30s: ~4M - after 5s: ~4M - after 5s: all remaining 92M Some analyze shows that the internal io dispatch queues goes like this: s_io s_more_io ------------------------- 1) 100M,1K 0 2) 1K 96M 3) 0 96M 1) initial state with a 100M file and a 1K file 2) 4M written, nr_to_write <= 0, so write more 3) 1K written, nr_to_write > 0, no more writes(BUG) nr_to_write > 0 in (3) fools the upper layer to think that data have all been written out. The big dirty file is actually still sitting in s_more_io. We cannot simply splice s_more_io back to s_io as soon as s_io becomes empty, and let the loop in generic_sync_sb_inodes() continue: this may starve newly expired inodes in s_dirty. It is also not an option to draw inodes from both s_more_io and s_dirty, an let the loop go on: this might lead to live locks, and might also starve other superblocks in sync time(well kupdate may still starve some superblocks, that's another bug). We have to return when a full scan of s_io completes. So nr_to_write > 0 does not necessarily mean that "all data are written". This patch introduces a flag writeback_control.more_io to indicate that more io should be done. With it the big dirty file no longer has to wait for the next kupdate invokation 5s later. In sync_sb_inodes() we only set more_io on super_blocks we actually visited. This avoids the interaction between two pdflush deamons. Also in __sync_single_inode() we don't blindly keep requeuing the io if the filesystem cannot progress. Failing to do so may lead to 100% iowait. Tested-by: Mike Snitzer <snitzer@gmail.com> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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9p | ||
adfs | ||
affs | ||
afs | ||
autofs | ||
autofs4 | ||
befs | ||
bfs | ||
cifs | ||
coda | ||
configfs | ||
cramfs | ||
debugfs | ||
devpts | ||
dlm | ||
ecryptfs | ||
efs | ||
exportfs | ||
ext2 | ||
ext3 | ||
ext4 | ||
fat | ||
freevxfs | ||
fuse | ||
gfs2 | ||
hfs | ||
hfsplus | ||
hostfs | ||
hpfs | ||
hppfs | ||
hugetlbfs | ||
isofs | ||
jbd | ||
jbd2 | ||
jffs2 | ||
jfs | ||
lockd | ||
minix | ||
msdos | ||
ncpfs | ||
nfs | ||
nfs_common | ||
nfsd | ||
nls | ||
ntfs | ||
ocfs2 | ||
openpromfs | ||
partitions | ||
proc | ||
qnx4 | ||
ramfs | ||
reiserfs | ||
romfs | ||
smbfs | ||
sysfs | ||
sysv | ||
udf | ||
ufs | ||
vfat | ||
xfs | ||
aio.c | ||
anon_inodes.c | ||
attr.c | ||
bad_inode.c | ||
binfmt_aout.c | ||
binfmt_elf_fdpic.c | ||
binfmt_elf.c | ||
binfmt_em86.c | ||
binfmt_flat.c | ||
binfmt_misc.c | ||
binfmt_script.c | ||
binfmt_som.c | ||
bio.c | ||
block_dev.c | ||
buffer.c | ||
char_dev.c | ||
compat_binfmt_elf.c | ||
compat_ioctl.c | ||
compat.c | ||
dcache.c | ||
dcookies.c | ||
direct-io.c | ||
dnotify.c | ||
dquot.c | ||
drop_caches.c | ||
eventfd.c | ||
eventpoll.c | ||
exec.c | ||
fcntl.c | ||
fifo.c | ||
file_table.c | ||
file.c | ||
filesystems.c | ||
fs-writeback.c | ||
generic_acl.c | ||
inode.c | ||
inotify_user.c | ||
inotify.c | ||
internal.h | ||
ioctl.c | ||
ioprio.c | ||
Kconfig | ||
Kconfig.binfmt | ||
libfs.c | ||
locks.c | ||
Makefile | ||
mbcache.c | ||
mpage.c | ||
namei.c | ||
namespace.c | ||
nfsctl.c | ||
no-block.c | ||
open.c | ||
pipe.c | ||
pnode.c | ||
pnode.h | ||
posix_acl.c | ||
quota_v1.c | ||
quota_v2.c | ||
quota.c | ||
read_write.c | ||
read_write.h | ||
readdir.c | ||
select.c | ||
seq_file.c | ||
signalfd.c | ||
splice.c | ||
stack.c | ||
stat.c | ||
super.c | ||
sync.c | ||
timerfd.c | ||
utimes.c | ||
xattr_acl.c | ||
xattr.c |