Re: [Patch v2 03/15] CIFS: Use offset when reading pages
From: Tom Talpey
Date: Sat Jun 23 2018 - 21:58:50 EST
On 5/30/2018 3:47 PM, Long Li wrote:
From: Long Li <longli@xxxxxxxxxxxxx>
With offset defined in rdata, transport functions need to look at this
offset when reading data into the correct places in pages.
Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
---
fs/cifs/cifsproto.h | 4 +++-
fs/cifs/connect.c | 5 +++--
fs/cifs/file.c | 52 +++++++++++++++++++++++++++++++++++++---------------
fs/cifs/smb2ops.c | 2 +-
fs/cifs/smb2pdu.c | 1 +
5 files changed, 45 insertions(+), 19 deletions(-)
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index dc80f84..1f27d8e 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -203,7 +203,9 @@ extern void dequeue_mid(struct mid_q_entry *mid, bool malformed);
extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
unsigned int to_read);
extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
- struct page *page, unsigned int to_read);
+ struct page *page,
+ unsigned int page_offset,
+ unsigned int to_read);
extern int cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
struct cifs_sb_info *cifs_sb);
extern int cifs_match_super(struct super_block *, void *);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 83b0234..8501da0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -594,10 +594,11 @@ cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
int
cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
- unsigned int to_read)
+ unsigned int page_offset, unsigned int to_read)
{
struct msghdr smb_msg;
- struct bio_vec bv = {.bv_page = page, .bv_len = to_read};
+ struct bio_vec bv = {
+ .bv_page = page, .bv_len = to_read, .bv_offset = page_offset};
iov_iter_bvec(&smb_msg.msg_iter, READ | ITER_BVEC, &bv, 1, to_read);
return cifs_readv_from_socket(server, &smb_msg);
}
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 1c98293..87eece6 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3026,12 +3026,20 @@ uncached_fill_pages(struct TCP_Server_Info *server,
int result = 0;
unsigned int i;
unsigned int nr_pages = rdata->nr_pages;
+ unsigned int page_offset = rdata->page_offset;
rdata->got_bytes = 0;
rdata->tailsz = PAGE_SIZE;
for (i = 0; i < nr_pages; i++) {
struct page *page = rdata->pages[i];
size_t n;
+ unsigned int segment_size = rdata->pagesz;
+
+ if (i == 0)
+ segment_size -= page_offset;
+ else
+ page_offset = 0;
+
if (len <= 0) {
/* no need to hold page hostage */
@@ -3040,24 +3048,25 @@ uncached_fill_pages(struct TCP_Server_Info *server,
put_page(page);
continue;
}
+
n = len;
- if (len >= PAGE_SIZE) {
+ if (len >= segment_size)
/* enough data to fill the page */
- n = PAGE_SIZE;
- len -= n;
- } else {
- zero_user(page, len, PAGE_SIZE - len);
+ n = segment_size;
+ else
rdata->tailsz = len;
- len = 0;
- }
+ len -= n;
+
if (iter)
- result = copy_page_from_iter(page, 0, n, iter);
+ result = copy_page_from_iter(
+ page, page_offset, n, iter);
#ifdef CONFIG_CIFS_SMB_DIRECT
else if (rdata->mr)
result = n;
#endif
I hadn't noticed this type of xonditional code before. It's kind of ugly
to modify the data handling code like this. Do you plan to break this
out into an smbdirect-specific hander, like the cases above and below?
else
- result = cifs_read_page_from_socket(server, page, n);
+ result = cifs_read_page_from_socket(
+ server, page, page_offset, n);
if (result < 0)
break;
@@ -3130,6 +3139,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
rdata->bytes = cur_len;
rdata->pid = pid;
rdata->pagesz = PAGE_SIZE;
+ rdata->tailsz = PAGE_SIZE;
rdata->read_into_pages = cifs_uncached_read_into_pages;
rdata->copy_into_pages = cifs_uncached_copy_into_pages;
rdata->credits = credits;
@@ -3574,6 +3584,7 @@ readpages_fill_pages(struct TCP_Server_Info *server,
u64 eof;
pgoff_t eof_index;
unsigned int nr_pages = rdata->nr_pages;
+ unsigned int page_offset = rdata->page_offset;
/* determine the eof that the server (probably) has */
eof = CIFS_I(rdata->mapping->host)->server_eof;
@@ -3584,13 +3595,21 @@ readpages_fill_pages(struct TCP_Server_Info *server,
rdata->tailsz = PAGE_SIZE;
for (i = 0; i < nr_pages; i++) {
struct page *page = rdata->pages[i];
- size_t n = PAGE_SIZE;
+ unsigned int to_read = rdata->pagesz;
+ size_t n;
+
+ if (i == 0)
+ to_read -= page_offset;
+ else
+ page_offset = 0;
+
+ n = to_read;
- if (len >= PAGE_SIZE) {
- len -= PAGE_SIZE;
+ if (len >= to_read) {
+ len -= to_read;
} else if (len > 0) {
/* enough for partial page, fill and zero the rest */
- zero_user(page, len, PAGE_SIZE - len);
+ zero_user(page, len + page_offset, to_read - len);
n = rdata->tailsz = len;
len = 0;
} else if (page->index > eof_index) {
@@ -3622,13 +3641,15 @@ readpages_fill_pages(struct TCP_Server_Info *server,
}
if (iter)
- result = copy_page_from_iter(page, 0, n, iter);
+ result = copy_page_from_iter(
+ page, page_offset, n, iter);
#ifdef CONFIG_CIFS_SMB_DIRECT
else if (rdata->mr)
result = n;
#endif
Ditto previous comment/question.
else
- result = cifs_read_page_from_socket(server, page, n);
+ result = cifs_read_page_from_socket(
+ server, page, page_offset, n);
if (result < 0)
break;
@@ -3807,6 +3828,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
rdata->bytes = bytes;
rdata->pid = pid;
rdata->pagesz = PAGE_SIZE;
+ rdata->tailsz = PAGE_SIZE;
rdata->read_into_pages = cifs_readpages_read_into_pages;
rdata->copy_into_pages = cifs_readpages_copy_into_pages;
rdata->credits = credits;
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 7c0edd2..1fa1c29 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2467,7 +2467,7 @@ read_data_into_pages(struct TCP_Server_Info *server, struct page **pages,
zero_user(page, len, PAGE_SIZE - len);
len = 0;
}
- length = cifs_read_page_from_socket(server, page, n);
+ length = cifs_read_page_from_socket(server, page, 0, n);
if (length < 0)
return length;
server->total_read += length;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index a02f6b6..f603fbe 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2683,6 +2683,7 @@ smb2_readv_callback(struct mid_q_entry *mid)
struct smb_rqst rqst = { .rq_iov = rdata->iov,
.rq_nvec = 2,
.rq_pages = rdata->pages,
+ .rq_offset = rdata->page_offset,
.rq_npages = rdata->nr_pages,
.rq_pagesz = rdata->pagesz,
.rq_tailsz = rdata->tailsz };