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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2006-06-23 05:03:26 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 10:42:49 -0400
commit111ebb6e6f7bd7de6d722c5848e95621f43700d9 (patch)
treebb00b13001db9be201e9b6d31468a79f4d1240bf /fs/cifs
parent4c91c3648c620003cb7b21b8858f36cd6132e168 (diff)
[PATCH] writeback: fix range handling
When a writeback_control's `start' and `end' fields are used to indicate a one-byte-range starting at file offset zero, the required values of .start=0,.end=0 mean that the ->writepages() implementation has no way of telling that it is being asked to perform a range request. Because we're currently overloading (start == 0 && end == 0) to mean "this is not a write-a-range request". To make all this sane, the patch changes range of writeback_control. So caller does: If it is calling ->writepages() to write pages, it sets range (range_start/end or range_cyclic) always. And if range_cyclic is true, ->writepages() thinks the range is cyclic, otherwise it just uses range_start and range_end. This patch does, - Add LLONG_MAX, LLONG_MIN, ULLONG_MAX to include/linux/kernel.h -1 is usually ok for range_end (type is long long). But, if someone did, range_end += val; range_end is "val - 1" u64val = range_end >> bits; u64val is "~(0ULL)" or something, they are wrong. So, this adds LLONG_MAX to avoid nasty things, and uses LLONG_MAX for range_end. - All callers of ->writepages() sets range_start/end or range_cyclic. - Fix updates of ->writeback_index. It seems already bit strange. If it starts at 0 and ended by check of nr_to_write, this last index may reduce chance to scan end of file. So, this updates ->writeback_index only if range_cyclic is true or whole-file is scanned. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Nathan Scott <nathans@sgi.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Steven French <sfrench@us.ibm.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/cifs')
-rw-r--r--fs/cifs/file.c24
1 files changed, 11 insertions, 13 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index e2b4ce1dad66..487ea8b3baaa 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1079,9 +1079,9 @@ static int cifs_writepages(struct address_space *mapping,
1079 unsigned int bytes_written; 1079 unsigned int bytes_written;
1080 struct cifs_sb_info *cifs_sb; 1080 struct cifs_sb_info *cifs_sb;
1081 int done = 0; 1081 int done = 0;
1082 pgoff_t end = -1; 1082 pgoff_t end;
1083 pgoff_t index; 1083 pgoff_t index;
1084 int is_range = 0; 1084 int range_whole = 0;
1085 struct kvec iov[32]; 1085 struct kvec iov[32];
1086 int len; 1086 int len;
1087 int n_iov = 0; 1087 int n_iov = 0;
@@ -1122,16 +1122,14 @@ static int cifs_writepages(struct address_space *mapping,
1122 xid = GetXid(); 1122 xid = GetXid();
1123 1123
1124 pagevec_init(&pvec, 0); 1124 pagevec_init(&pvec, 0);
1125 if (wbc->sync_mode == WB_SYNC_NONE) 1125 if (wbc->range_cyclic) {
1126 index = mapping->writeback_index; /* Start from prev offset */ 1126 index = mapping->writeback_index; /* Start from prev offset */
1127 else { 1127 end = -1;
1128 index = 0; 1128 } else {
1129 scanned = 1; 1129 index = wbc->range_start >> PAGE_CACHE_SHIFT;
1130 } 1130 end = wbc->range_end >> PAGE_CACHE_SHIFT;
1131 if (wbc->start || wbc->end) { 1131 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
1132 index = wbc->start >> PAGE_CACHE_SHIFT; 1132 range_whole = 1;
1133 end = wbc->end >> PAGE_CACHE_SHIFT;
1134 is_range = 1;
1135 scanned = 1; 1133 scanned = 1;
1136 } 1134 }
1137retry: 1135retry:
@@ -1167,7 +1165,7 @@ retry:
1167 break; 1165 break;
1168 } 1166 }
1169 1167
1170 if (unlikely(is_range) && (page->index > end)) { 1168 if (!wbc->range_cyclic && page->index > end) {
1171 done = 1; 1169 done = 1;
1172 unlock_page(page); 1170 unlock_page(page);
1173 break; 1171 break;
@@ -1271,7 +1269,7 @@ retry:
1271 index = 0; 1269 index = 0;
1272 goto retry; 1270 goto retry;
1273 } 1271 }
1274 if (!is_range) 1272 if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
1275 mapping->writeback_index = index; 1273 mapping->writeback_index = index;
1276 1274
1277 FreeXid(xid); 1275 FreeXid(xid);