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fs: handle delegated timestamps in setattr_copy_mgtime
An update to the inode ctime typically requires the latest clock value possible. The exception to this rule is when there is a nfsd write delegation and the server is proxying timestamps from the client. When nfsd gets a CB_GETATTR response, update the timestamp value in the inode to the values that the client is tracking. The client doesn't send a ctime value (since that's always determined by the exported filesystem), but it can send a mtime value. In the case where it does, update the ctime to a value commensurate with that instead of the current time. If ATTR_DELEG is set, then use ia_ctime value instead of setting the timestamp to the current time. With the addition of delegated timestamps, the server may receive a request to update only the atime, which doesn't involve a ctime update. Trust the ATTR_CTIME flag in the update and only update the ctime when it's set. Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jeff Layton <jlayton@kernel.org> Link: https://lore.kernel.org/r/20241002-mgtime-v10-5-d1c4717f5284@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
parent
b82f92d5dd
commit
7f2c86cba3
29
fs/attr.c
29
fs/attr.c
@ -286,16 +286,21 @@ static void setattr_copy_mgtime(struct inode *inode, const struct iattr *attr)
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unsigned int ia_valid = attr->ia_valid;
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unsigned int ia_valid = attr->ia_valid;
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struct timespec64 now;
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struct timespec64 now;
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/*
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if (ia_valid & ATTR_CTIME) {
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* If the ctime isn't being updated then nothing else should be
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/*
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* either.
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* In the case of an update for a write delegation, we must respect
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*/
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* the value in ia_ctime and not use the current time.
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if (!(ia_valid & ATTR_CTIME)) {
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*/
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WARN_ON_ONCE(ia_valid & (ATTR_ATIME|ATTR_MTIME));
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if (ia_valid & ATTR_DELEG)
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return;
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now = inode_set_ctime_deleg(inode, attr->ia_ctime);
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else
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now = inode_set_ctime_current(inode);
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} else {
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/* If ATTR_CTIME isn't set, then ATTR_MTIME shouldn't be either. */
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WARN_ON_ONCE(ia_valid & ATTR_MTIME);
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now = current_time(inode);
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}
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}
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now = inode_set_ctime_current(inode);
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if (ia_valid & ATTR_ATIME_SET)
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if (ia_valid & ATTR_ATIME_SET)
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inode_set_atime_to_ts(inode, attr->ia_atime);
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inode_set_atime_to_ts(inode, attr->ia_atime);
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else if (ia_valid & ATTR_ATIME)
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else if (ia_valid & ATTR_ATIME)
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@ -354,8 +359,12 @@ void setattr_copy(struct mnt_idmap *idmap, struct inode *inode,
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inode_set_atime_to_ts(inode, attr->ia_atime);
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inode_set_atime_to_ts(inode, attr->ia_atime);
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if (ia_valid & ATTR_MTIME)
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if (ia_valid & ATTR_MTIME)
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inode_set_mtime_to_ts(inode, attr->ia_mtime);
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inode_set_mtime_to_ts(inode, attr->ia_mtime);
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if (ia_valid & ATTR_CTIME)
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if (ia_valid & ATTR_CTIME) {
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inode_set_ctime_to_ts(inode, attr->ia_ctime);
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if (ia_valid & ATTR_DELEG)
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inode_set_ctime_deleg(inode, attr->ia_ctime);
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else
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inode_set_ctime_to_ts(inode, attr->ia_ctime);
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}
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}
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}
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EXPORT_SYMBOL(setattr_copy);
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EXPORT_SYMBOL(setattr_copy);
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73
fs/inode.c
73
fs/inode.c
@ -2717,6 +2717,79 @@ struct timespec64 inode_set_ctime_current(struct inode *inode)
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}
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}
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EXPORT_SYMBOL(inode_set_ctime_current);
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EXPORT_SYMBOL(inode_set_ctime_current);
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/**
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* inode_set_ctime_deleg - try to update the ctime on a delegated inode
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* @inode: inode to update
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* @update: timespec64 to set the ctime
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*
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* Attempt to atomically update the ctime on behalf of a delegation holder.
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*
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* The nfs server can call back the holder of a delegation to get updated
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* inode attributes, including the mtime. When updating the mtime, update
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* the ctime to a value at least equal to that.
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*
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* This can race with concurrent updates to the inode, in which
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* case the update is skipped.
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*
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* Note that this works even when multigrain timestamps are not enabled,
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* so it is used in either case.
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*/
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struct timespec64 inode_set_ctime_deleg(struct inode *inode, struct timespec64 update)
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{
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struct timespec64 now, cur_ts;
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u32 cur, old;
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/* pairs with try_cmpxchg below */
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cur = smp_load_acquire(&inode->i_ctime_nsec);
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cur_ts.tv_nsec = cur & ~I_CTIME_QUERIED;
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cur_ts.tv_sec = inode->i_ctime_sec;
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/* If the update is older than the existing value, skip it. */
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if (timespec64_compare(&update, &cur_ts) <= 0)
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return cur_ts;
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ktime_get_coarse_real_ts64_mg(&now);
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/* Clamp the update to "now" if it's in the future */
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if (timespec64_compare(&update, &now) > 0)
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update = now;
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update = timestamp_truncate(update, inode);
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/* No need to update if the values are already the same */
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if (timespec64_equal(&update, &cur_ts))
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return cur_ts;
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/*
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* Try to swap the nsec value into place. If it fails, that means
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* it raced with an update due to a write or similar activity. That
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* stamp takes precedence, so just skip the update.
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*/
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retry:
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old = cur;
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if (try_cmpxchg(&inode->i_ctime_nsec, &cur, update.tv_nsec)) {
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inode->i_ctime_sec = update.tv_sec;
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mgtime_counter_inc(mg_ctime_swaps);
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return update;
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}
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/*
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* Was the change due to another task marking the old ctime QUERIED?
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*
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* If so, then retry the swap. This can only happen once since
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* the only way to clear I_CTIME_QUERIED is to stamp the inode
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* with a new ctime.
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*/
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if (!(old & I_CTIME_QUERIED) && (cur == (old | I_CTIME_QUERIED)))
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goto retry;
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/* Otherwise, it was a new timestamp. */
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cur_ts.tv_sec = inode->i_ctime_sec;
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cur_ts.tv_nsec = cur & ~I_CTIME_QUERIED;
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return cur_ts;
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}
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EXPORT_SYMBOL(inode_set_ctime_deleg);
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/**
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/**
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* in_group_or_capable - check whether caller is CAP_FSETID privileged
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* in_group_or_capable - check whether caller is CAP_FSETID privileged
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* @idmap: idmap of the mount @inode was found from
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* @idmap: idmap of the mount @inode was found from
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@ -1544,6 +1544,8 @@ static inline bool fsuidgid_has_mapping(struct super_block *sb,
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struct timespec64 current_time(struct inode *inode);
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struct timespec64 current_time(struct inode *inode);
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struct timespec64 inode_set_ctime_current(struct inode *inode);
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struct timespec64 inode_set_ctime_current(struct inode *inode);
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struct timespec64 inode_set_ctime_deleg(struct inode *inode,
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struct timespec64 update);
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static inline time64_t inode_get_atime_sec(const struct inode *inode)
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static inline time64_t inode_get_atime_sec(const struct inode *inode)
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{
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{
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