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| author |   Ronnie Sahlberg <lsahlber@redhat.com> | 2017-11-21 15:08:07 +1100 |
|---|---|---|
| committer |   Steve French <smfrench@gmail.com> | 2018-01-24 19:49:05 -0600 |
| commit | 3cecf4865cd3ea31272750edf38e73c59ff7540c (patch) | |
| tree | e3d41786d5e4390eaae2b1def522ca9f65a47dff /fs | |
| parent | cifs: remove small_smb2_init (diff) | |
| download | linux-dev-3cecf4865cd3ea31272750edf38e73c59ff7540c.tar.xz linux-dev-3cecf4865cd3ea31272750edf38e73c59ff7540c.zip | |
cifs: avoid a kmalloc in smb2_send_recv/SendReceive2 for the common case
In both functions, use an array of 8 (arbitrary but should be big enough
for all current uses) iov and avoid having to kmalloc the array
for the common case.
If 8 is too small, then fall back to the original behaviour and use
kmalloc/kfree.
This should not change any behaviour but should save us a tiny amount of
cpu cycles.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/cifs/transport.c | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index e678307bb7a0..510f41a435c8 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -38,6 +38,9 @@ #include "cifsproto.h" #include "cifs_debug.h" +/* Max number of iovectors we can use off the stack when sending requests. */ +#define CIFS_MAX_IOV_SIZE 8 + void cifs_wake_up_task(struct mid_q_entry *mid) { @@ -803,12 +806,16 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses, const int flags, struct kvec *resp_iov) { struct smb_rqst rqst; - struct kvec *new_iov; + struct kvec s_iov[CIFS_MAX_IOV_SIZE], *new_iov; int rc; - new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), GFP_KERNEL); - if (!new_iov) - return -ENOMEM; + if (n_vec + 1 > CIFS_MAX_IOV_SIZE) { + new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), + GFP_KERNEL); + if (!new_iov) + return -ENOMEM; + } else + new_iov = s_iov; /* 1st iov is a RFC1001 length followed by the rest of the packet */ memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec)); @@ -823,7 +830,8 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses, rqst.rq_nvec = n_vec + 1; rc = cifs_send_recv(xid, ses, &rqst, resp_buf_type, flags, resp_iov); - kfree(new_iov); + if (n_vec + 1 > CIFS_MAX_IOV_SIZE) + kfree(new_iov); return rc; } @@ -834,15 +842,19 @@ smb2_send_recv(const unsigned int xid, struct cifs_ses *ses, const int flags, struct kvec *resp_iov) { struct smb_rqst rqst; - struct kvec *new_iov; + struct kvec s_iov[CIFS_MAX_IOV_SIZE], *new_iov; int rc; int i; __u32 count; __be32 rfc1002_marker; - new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), GFP_KERNEL); - if (!new_iov) - return -ENOMEM; + if (n_vec + 1 > CIFS_MAX_IOV_SIZE) { + new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), + GFP_KERNEL); + if (!new_iov) + return -ENOMEM; + } else + new_iov = s_iov; /* 1st iov is an RFC1002 Session Message length */ memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec)); @@ -861,7 +873,8 @@ smb2_send_recv(const unsigned int xid, struct cifs_ses *ses, rqst.rq_nvec = n_vec + 1; rc = cifs_send_recv(xid, ses, &rqst, resp_buf_type, flags, resp_iov); - kfree(new_iov); + if (n_vec + 1 > CIFS_MAX_IOV_SIZE) + kfree(new_iov); return rc; } |