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authorAndreas Gruenbacher <agruenba@redhat.com>2022-05-05 00:37:30 +0300
committerAndreas Gruenbacher <agruenba@redhat.com>2022-05-13 23:32:52 +0300
commitfa5dfa645d85910d747f4e0c97f19e5e97d1c270 (patch)
tree28e84df2c127259d0e317881e1a4c4ceb1698f05 /fs
parent324d116c5a5c8204dc00e63f725a3c5ed09afb53 (diff)
downloadlinux-fa5dfa645d85910d747f4e0c97f19e5e97d1c270.tar.xz
gfs2: buffered write prefaulting
In gfs2_file_buffered_write, to increase the likelihood that all the user memory we're trying to write will be resident in memory, carry out the write in chunks and fault in each chunk of user memory before trying to write it. Otherwise, some workloads will trigger frequent short "internal" writes, causing filesystem blocks to be allocated and then partially deallocated again when writing into holes, which is wasteful and breaks reservations. Neither the chunked writes nor any of the short "internal" writes are user visible. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/gfs2/file.c28
1 files changed, 16 insertions, 12 deletions
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 11c46407d4a8..5eda1bcc85e3 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -778,7 +778,7 @@ static inline bool should_fault_in_pages(struct iov_iter *i,
size_t count = iov_iter_count(i);
size_t size, offs;
- if (likely(!count))
+ if (!count)
return false;
if (!iter_is_iovec(i))
return false;
@@ -1033,7 +1033,20 @@ retry:
ret = gfs2_glock_nq(gh);
if (ret)
goto out_uninit;
+ if (should_fault_in_pages(from, iocb, &prev_count, &window_size)) {
retry_under_glock:
+ gfs2_holder_allow_demote(gh);
+ window_size -= fault_in_iov_iter_readable(from, window_size);
+ gfs2_holder_disallow_demote(gh);
+ if (!window_size) {
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+ if (!gfs2_holder_queued(gh))
+ goto retry;
+ from->count = min(from->count, window_size);
+ }
+
if (inode == sdp->sd_rindex) {
struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
@@ -1060,17 +1073,8 @@ retry_under_glock:
goto out_unlock;
from->count = orig_count - written;
- if (should_fault_in_pages(from, iocb, &prev_count, &window_size)) {
- gfs2_holder_allow_demote(gh);
- window_size -= fault_in_iov_iter_readable(from, window_size);
- gfs2_holder_disallow_demote(gh);
- if (window_size) {
- from->count = min(from->count, window_size);
- if (gfs2_holder_queued(gh))
- goto retry_under_glock;
- goto retry;
- }
- }
+ if (should_fault_in_pages(from, iocb, &prev_count, &window_size))
+ goto retry_under_glock;
out_unlock:
if (gfs2_holder_queued(gh))
gfs2_glock_dq(gh);