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* [PATCH RESEND] nfs: prevent truncate on active swapfile @ 2015-01-08 9:18 Omar Sandoval 2015-01-10 22:08 ` Trond Myklebust 0 siblings, 1 reply; 6+ messages in thread From: Omar Sandoval @ 2015-01-08 9:18 UTC (permalink / raw) To: Trond Myklebust, linux-nfs, linux-kernel Cc: Al Viro, linux-fsdevel, Omar Sandoval Most filesystems prevent truncation of an active swapfile by way of inode_newsize_ok, called from inode_change_ok. NFS doesn't call either from nfs_setattr, presumably because most of these checks are expected to be done server-side. However, the IS_SWAPFILE check can only be done client-side, and truncating a swapfile can't possibly be good. Signed-off-by: Omar Sandoval <osandov@osandov.com> --- Hi, Trond, Now that the holidays are over, could you take a look at this? It was generated against v3.19-rc3. Thanks! fs/nfs/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 4bffe63..9205513 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr) attr->ia_valid &= ~ATTR_MODE; if (attr->ia_valid & ATTR_SIZE) { + loff_t i_size; + BUG_ON(!S_ISREG(inode->i_mode)); - if (attr->ia_size == i_size_read(inode)) + i_size = i_size_read(inode); + if (attr->ia_size == i_size) attr->ia_valid &= ~ATTR_SIZE; + else if (attr->ia_size < i_size && IS_SWAPFILE(inode)) + return -ETXTBSY; } /* Optimization: if the end result is no change, don't RPC */ -- 2.2.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND] nfs: prevent truncate on active swapfile 2015-01-08 9:18 [PATCH RESEND] nfs: prevent truncate on active swapfile Omar Sandoval @ 2015-01-10 22:08 ` Trond Myklebust 2015-01-12 19:43 ` Omar Sandoval 0 siblings, 1 reply; 6+ messages in thread From: Trond Myklebust @ 2015-01-10 22:08 UTC (permalink / raw) To: Omar Sandoval Cc: Linux NFS Mailing List, Linux Kernel mailing list, Al Viro, Devel FS Linux Hi Omar, On Thu, Jan 8, 2015 at 4:18 AM, Omar Sandoval <osandov@osandov.com> wrote: > Most filesystems prevent truncation of an active swapfile by way of > inode_newsize_ok, called from inode_change_ok. NFS doesn't call either > from nfs_setattr, presumably because most of these checks are expected > to be done server-side. However, the IS_SWAPFILE check can only be done > client-side, and truncating a swapfile can't possibly be good. > > Signed-off-by: Omar Sandoval <osandov@osandov.com> > --- > Hi, Trond, > > Now that the holidays are over, could you take a look at this? It was > generated against v3.19-rc3. > > Thanks! > > fs/nfs/inode.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c > index 4bffe63..9205513 100644 > --- a/fs/nfs/inode.c > +++ b/fs/nfs/inode.c > @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr) > attr->ia_valid &= ~ATTR_MODE; > > if (attr->ia_valid & ATTR_SIZE) { > + loff_t i_size; > + > BUG_ON(!S_ISREG(inode->i_mode)); > > - if (attr->ia_size == i_size_read(inode)) > + i_size = i_size_read(inode); > + if (attr->ia_size == i_size) > attr->ia_valid &= ~ATTR_SIZE; > + else if (attr->ia_size < i_size && IS_SWAPFILE(inode)) > + return -ETXTBSY; > } > > /* Optimization: if the end result is no change, don't RPC */ > -- > 2.2.1 > I agree that truncating a swap file is bad, however as you point out, this really only addresses the case on the client that knows about this being a swap file. I'll take the patch, but I'm wondering if we couldn't do better in the case where we're using NFSv4 by using share deny modes (which are enforced by the server). The problem is that there appears to be nothing in swapon() that tells the filesystem this is an open of a swap file... Cheers Trond -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND] nfs: prevent truncate on active swapfile 2015-01-10 22:08 ` Trond Myklebust @ 2015-01-12 19:43 ` Omar Sandoval 2015-01-23 4:07 ` Omar Sandoval 0 siblings, 1 reply; 6+ messages in thread From: Omar Sandoval @ 2015-01-12 19:43 UTC (permalink / raw) To: Trond Myklebust Cc: Linux NFS Mailing List, Linux Kernel mailing list, Al Viro, Devel FS Linux On Sat, Jan 10, 2015 at 05:08:03PM -0500, Trond Myklebust wrote: > Hi Omar, > > On Thu, Jan 8, 2015 at 4:18 AM, Omar Sandoval <osandov@osandov.com> wrote: > > Most filesystems prevent truncation of an active swapfile by way of > > inode_newsize_ok, called from inode_change_ok. NFS doesn't call either > > from nfs_setattr, presumably because most of these checks are expected > > to be done server-side. However, the IS_SWAPFILE check can only be done > > client-side, and truncating a swapfile can't possibly be good. > > > > Signed-off-by: Omar Sandoval <osandov@osandov.com> > > --- > > Hi, Trond, > > > > Now that the holidays are over, could you take a look at this? It was > > generated against v3.19-rc3. > > > > Thanks! > > > > fs/nfs/inode.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c > > index 4bffe63..9205513 100644 > > --- a/fs/nfs/inode.c > > +++ b/fs/nfs/inode.c > > @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr) > > attr->ia_valid &= ~ATTR_MODE; > > > > if (attr->ia_valid & ATTR_SIZE) { > > + loff_t i_size; > > + > > BUG_ON(!S_ISREG(inode->i_mode)); > > > > - if (attr->ia_size == i_size_read(inode)) > > + i_size = i_size_read(inode); > > + if (attr->ia_size == i_size) > > attr->ia_valid &= ~ATTR_SIZE; > > + else if (attr->ia_size < i_size && IS_SWAPFILE(inode)) > > + return -ETXTBSY; > > } > > > > /* Optimization: if the end result is no change, don't RPC */ > > -- > > 2.2.1 > > > > I agree that truncating a swap file is bad, however as you point out, > this really only addresses the case on the client that knows about > this being a swap file. > I'll take the patch, Thanks, I appreciate it. > but I'm wondering if we couldn't do better in the > case where we're using NFSv4 by using share deny modes (which are > enforced by the server). The problem is that there appears to be > nothing in swapon() that tells the filesystem this is an open of a > swap file... Yeah, it would be nice for completeness to prevent one client from truncating another client's swapfile. However, I'd hope that anyone using swap-over-NFS on a shared NFS mount would take the necessary precautions in terms of permissions, etc. to prevent someone from doing that. Also, since the failure mode of truncating an NFS swapfile is a corrupt swapfile rather than a corrupt filesystem (like on a local filesystem), it's probably okay to just deal with the low-hanging fruit for now. Thanks! > > Cheers > Trond > -- > Trond Myklebust > Linux NFS client maintainer, PrimaryData > trond.myklebust@primarydata.com -- Omar ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND] nfs: prevent truncate on active swapfile 2015-01-12 19:43 ` Omar Sandoval @ 2015-01-23 4:07 ` Omar Sandoval 2015-01-23 13:07 ` Trond Myklebust 0 siblings, 1 reply; 6+ messages in thread From: Omar Sandoval @ 2015-01-23 4:07 UTC (permalink / raw) To: Trond Myklebust Cc: Linux NFS Mailing List, Linux Kernel mailing list, Al Viro, Devel FS Linux On Mon, Jan 12, 2015 at 11:43:02AM -0800, Omar Sandoval wrote: > On Sat, Jan 10, 2015 at 05:08:03PM -0500, Trond Myklebust wrote: > > Hi Omar, > > > > On Thu, Jan 8, 2015 at 4:18 AM, Omar Sandoval <osandov@osandov.com> wrote: > > > Most filesystems prevent truncation of an active swapfile by way of > > > inode_newsize_ok, called from inode_change_ok. NFS doesn't call either > > > from nfs_setattr, presumably because most of these checks are expected > > > to be done server-side. However, the IS_SWAPFILE check can only be done > > > client-side, and truncating a swapfile can't possibly be good. > > > > > > Signed-off-by: Omar Sandoval <osandov@osandov.com> > > > --- > > > Hi, Trond, > > > > > > Now that the holidays are over, could you take a look at this? It was > > > generated against v3.19-rc3. > > > > > > Thanks! > > > > > > fs/nfs/inode.c | 7 ++++++- > > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c > > > index 4bffe63..9205513 100644 > > > --- a/fs/nfs/inode.c > > > +++ b/fs/nfs/inode.c > > > @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr) > > > attr->ia_valid &= ~ATTR_MODE; > > > > > > if (attr->ia_valid & ATTR_SIZE) { > > > + loff_t i_size; > > > + > > > BUG_ON(!S_ISREG(inode->i_mode)); > > > > > > - if (attr->ia_size == i_size_read(inode)) > > > + i_size = i_size_read(inode); > > > + if (attr->ia_size == i_size) > > > attr->ia_valid &= ~ATTR_SIZE; > > > + else if (attr->ia_size < i_size && IS_SWAPFILE(inode)) > > > + return -ETXTBSY; > > > } > > > > > > /* Optimization: if the end result is no change, don't RPC */ > > > -- > > > 2.2.1 > > > > > > > I agree that truncating a swap file is bad, however as you point out, > > this really only addresses the case on the client that knows about > > this being a swap file. > > I'll take the patch, > > Thanks, I appreciate it. > > > but I'm wondering if we couldn't do better in the > > case where we're using NFSv4 by using share deny modes (which are > > enforced by the server). The problem is that there appears to be > > nothing in swapon() that tells the filesystem this is an open of a > > swap file... > > Yeah, it would be nice for completeness to prevent one client from > truncating another client's swapfile. However, I'd hope that anyone > using swap-over-NFS on a shared NFS mount would take the necessary > precautions in terms of permissions, etc. to prevent someone from doing > that. Also, since the failure mode of truncating an NFS swapfile is a > corrupt swapfile rather than a corrupt filesystem (like on a local > filesystem), it's probably okay to just deal with the low-hanging fruit > for now. > > Thanks! > > > > > Cheers > > Trond > > -- > > Trond Myklebust > > Linux NFS client maintainer, PrimaryData > > trond.myklebust@primarydata.com > > -- > Omar Hi, Trond, Are you still planning on taking this patch? I didn't see it in your last pull request to Linus. Thanks, -- Omar ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND] nfs: prevent truncate on active swapfile 2015-01-23 4:07 ` Omar Sandoval @ 2015-01-23 13:07 ` Trond Myklebust 2015-01-23 18:24 ` Omar Sandoval 0 siblings, 1 reply; 6+ messages in thread From: Trond Myklebust @ 2015-01-23 13:07 UTC (permalink / raw) To: Omar Sandoval Cc: Linux NFS Mailing List, Linux Kernel mailing list, Al Viro, Devel FS Linux On Thu, Jan 22, 2015 at 11:07 PM, Omar Sandoval <osandov@osandov.com> wrote: > On Mon, Jan 12, 2015 at 11:43:02AM -0800, Omar Sandoval wrote: >> On Sat, Jan 10, 2015 at 05:08:03PM -0500, Trond Myklebust wrote: >> > Hi Omar, >> > >> > On Thu, Jan 8, 2015 at 4:18 AM, Omar Sandoval <osandov@osandov.com> wrote: >> > > Most filesystems prevent truncation of an active swapfile by way of >> > > inode_newsize_ok, called from inode_change_ok. NFS doesn't call either >> > > from nfs_setattr, presumably because most of these checks are expected >> > > to be done server-side. However, the IS_SWAPFILE check can only be done >> > > client-side, and truncating a swapfile can't possibly be good. >> > > >> > > Signed-off-by: Omar Sandoval <osandov@osandov.com> >> > > --- >> > > Hi, Trond, >> > > >> > > Now that the holidays are over, could you take a look at this? It was >> > > generated against v3.19-rc3. >> > > >> > > Thanks! >> > > >> > > fs/nfs/inode.c | 7 ++++++- >> > > 1 file changed, 6 insertions(+), 1 deletion(-) >> > > >> > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c >> > > index 4bffe63..9205513 100644 >> > > --- a/fs/nfs/inode.c >> > > +++ b/fs/nfs/inode.c >> > > @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr) >> > > attr->ia_valid &= ~ATTR_MODE; >> > > >> > > if (attr->ia_valid & ATTR_SIZE) { >> > > + loff_t i_size; >> > > + >> > > BUG_ON(!S_ISREG(inode->i_mode)); >> > > >> > > - if (attr->ia_size == i_size_read(inode)) >> > > + i_size = i_size_read(inode); >> > > + if (attr->ia_size == i_size) >> > > attr->ia_valid &= ~ATTR_SIZE; >> > > + else if (attr->ia_size < i_size && IS_SWAPFILE(inode)) >> > > + return -ETXTBSY; >> > > } >> > > >> > > /* Optimization: if the end result is no change, don't RPC */ >> > > -- >> > > 2.2.1 >> > > >> > >> > I agree that truncating a swap file is bad, however as you point out, >> > this really only addresses the case on the client that knows about >> > this being a swap file. >> > I'll take the patch, >> >> Thanks, I appreciate it. >> >> > but I'm wondering if we couldn't do better in the >> > case where we're using NFSv4 by using share deny modes (which are >> > enforced by the server). The problem is that there appears to be >> > nothing in swapon() that tells the filesystem this is an open of a >> > swap file... >> >> Yeah, it would be nice for completeness to prevent one client from >> truncating another client's swapfile. However, I'd hope that anyone >> using swap-over-NFS on a shared NFS mount would take the necessary >> precautions in terms of permissions, etc. to prevent someone from doing >> that. Also, since the failure mode of truncating an NFS swapfile is a >> corrupt swapfile rather than a corrupt filesystem (like on a local >> filesystem), it's probably okay to just deal with the low-hanging fruit >> for now. >> >> Thanks! >> >> > >> > Cheers >> > Trond >> > -- >> > Trond Myklebust >> > Linux NFS client maintainer, PrimaryData >> > trond.myklebust@primarydata.com >> >> -- >> Omar > > Hi, Trond, > > Are you still planning on taking this patch? I didn't see it in your > last pull request to Linus. I was planning on pushing it in the 3.20 merge window. Is there any reason to fasttrack it earlier as an important bugfix? To me it seems more like an "assist user to not shoot self in foot" type of thing. Cheers Trond -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND] nfs: prevent truncate on active swapfile 2015-01-23 13:07 ` Trond Myklebust @ 2015-01-23 18:24 ` Omar Sandoval 0 siblings, 0 replies; 6+ messages in thread From: Omar Sandoval @ 2015-01-23 18:24 UTC (permalink / raw) To: Trond Myklebust Cc: Linux NFS Mailing List, Linux Kernel mailing list, Al Viro, Devel FS Linux On Fri, Jan 23, 2015 at 08:07:41AM -0500, Trond Myklebust wrote: > On Thu, Jan 22, 2015 at 11:07 PM, Omar Sandoval <osandov@osandov.com> wrote: > > On Mon, Jan 12, 2015 at 11:43:02AM -0800, Omar Sandoval wrote: > >> On Sat, Jan 10, 2015 at 05:08:03PM -0500, Trond Myklebust wrote: > >> > Hi Omar, > >> > > >> > On Thu, Jan 8, 2015 at 4:18 AM, Omar Sandoval <osandov@osandov.com> wrote: > >> > > Most filesystems prevent truncation of an active swapfile by way of > >> > > inode_newsize_ok, called from inode_change_ok. NFS doesn't call either > >> > > from nfs_setattr, presumably because most of these checks are expected > >> > > to be done server-side. However, the IS_SWAPFILE check can only be done > >> > > client-side, and truncating a swapfile can't possibly be good. > >> > > > >> > > Signed-off-by: Omar Sandoval <osandov@osandov.com> > >> > > --- > >> > > Hi, Trond, > >> > > > >> > > Now that the holidays are over, could you take a look at this? It was > >> > > generated against v3.19-rc3. > >> > > > >> > > Thanks! > >> > > > >> > > fs/nfs/inode.c | 7 ++++++- > >> > > 1 file changed, 6 insertions(+), 1 deletion(-) > >> > > > >> > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c > >> > > index 4bffe63..9205513 100644 > >> > > --- a/fs/nfs/inode.c > >> > > +++ b/fs/nfs/inode.c > >> > > @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr) > >> > > attr->ia_valid &= ~ATTR_MODE; > >> > > > >> > > if (attr->ia_valid & ATTR_SIZE) { > >> > > + loff_t i_size; > >> > > + > >> > > BUG_ON(!S_ISREG(inode->i_mode)); > >> > > > >> > > - if (attr->ia_size == i_size_read(inode)) > >> > > + i_size = i_size_read(inode); > >> > > + if (attr->ia_size == i_size) > >> > > attr->ia_valid &= ~ATTR_SIZE; > >> > > + else if (attr->ia_size < i_size && IS_SWAPFILE(inode)) > >> > > + return -ETXTBSY; > >> > > } > >> > > > >> > > /* Optimization: if the end result is no change, don't RPC */ > >> > > -- > >> > > 2.2.1 > >> > > > >> > > >> > I agree that truncating a swap file is bad, however as you point out, > >> > this really only addresses the case on the client that knows about > >> > this being a swap file. > >> > I'll take the patch, > >> > >> Thanks, I appreciate it. > >> > >> > but I'm wondering if we couldn't do better in the > >> > case where we're using NFSv4 by using share deny modes (which are > >> > enforced by the server). The problem is that there appears to be > >> > nothing in swapon() that tells the filesystem this is an open of a > >> > swap file... > >> > >> Yeah, it would be nice for completeness to prevent one client from > >> truncating another client's swapfile. However, I'd hope that anyone > >> using swap-over-NFS on a shared NFS mount would take the necessary > >> precautions in terms of permissions, etc. to prevent someone from doing > >> that. Also, since the failure mode of truncating an NFS swapfile is a > >> corrupt swapfile rather than a corrupt filesystem (like on a local > >> filesystem), it's probably okay to just deal with the low-hanging fruit > >> for now. > >> > >> Thanks! > >> > >> > > >> > Cheers > >> > Trond > >> > -- > >> > Trond Myklebust > >> > Linux NFS client maintainer, PrimaryData > >> > trond.myklebust@primarydata.com > >> > >> -- > >> Omar > > > > Hi, Trond, > > > > Are you still planning on taking this patch? I didn't see it in your > > last pull request to Linus. > > I was planning on pushing it in the 3.20 merge window. > > Is there any reason to fasttrack it earlier as an important bugfix? To > me it seems more like an "assist user to not shoot self in foot" type > of thing. > > Cheers > Trond > > -- > Trond Myklebust > Linux NFS client maintainer, PrimaryData > trond.myklebust@primarydata.com Ah, okay, 3.20 should be fine. Thanks, -- Omar ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2015-01-23 18:25 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-01-08 9:18 [PATCH RESEND] nfs: prevent truncate on active swapfile Omar Sandoval 2015-01-10 22:08 ` Trond Myklebust 2015-01-12 19:43 ` Omar Sandoval 2015-01-23 4:07 ` Omar Sandoval 2015-01-23 13:07 ` Trond Myklebust 2015-01-23 18:24 ` Omar Sandoval
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