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| author | Neil Brown <neilb@suse.de> | 2006-01-06 00:19:59 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-06 08:33:59 -0800 |
| commit | 9f708e40fe040e79f6c393a282f0701c9f8dc174 (patch) | |
| tree | e769b7b9088f03caf324923485ee1e5ef05e2292 /fs/nfsd | |
| parent | a334de28665b14f0a33df82699fa9a78cfeedf31 (diff) | |
| download | lwn-9f708e40fe040e79f6c393a282f0701c9f8dc174.tar.gz lwn-9f708e40fe040e79f6c393a282f0701c9f8dc174.zip | |
[PATCH] knfsd: reduce stack consumption
A typical nfsd call trace is
nfsd -> svc_process -> nfsd_dispatch -> nfsd3_proc_write ->
nfsd_write ->nfsd_vfs_write -> vfs_writev
These add up to over 300 bytes on the stack.
Looking at each of these, I see that nfsd_write (which includes
nfsd_vfs_write) contributes 0x8c to stack usage itself!!
It turns out this is because it puts a 'struct iattr' on the stack so
it can kill suid if needed. The following patch saves about 50 bytes
off the stack in this call path.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/nfsd')
| -rw-r--r-- | fs/nfsd/vfs.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index f83ab4cf4265..df4019f04560 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -880,6 +880,16 @@ out: return err; } +static void kill_suid(struct dentry *dentry) +{ + struct iattr ia; + ia.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID; + + down(&dentry->d_inode->i_sem); + notify_change(dentry, &ia); + up(&dentry->d_inode->i_sem); +} + static inline int nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, loff_t offset, struct kvec *vec, int vlen, @@ -933,14 +943,8 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, } /* clear setuid/setgid flag after write */ - if (err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID))) { - struct iattr ia; - ia.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID; - - down(&inode->i_sem); - notify_change(dentry, &ia); - up(&inode->i_sem); - } + if (err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID))) + kill_suid(dentry); if (err >= 0 && stable) { static ino_t last_ino; |