From 114a0a08d46cfb0eefb1a882f7866b7f57bfc5ba Mon Sep 17 00:00:00 2001 From: Bryan Schumaker Date: Tue, 1 Nov 2011 13:35:23 -0400 Subject: NFSD: Added fault injection documentation Signed-off-by: Bryan Schumaker Signed-off-by: J. Bruce Fields --- Documentation/filesystems/nfs/00-INDEX | 2 + Documentation/filesystems/nfs/fault_injection.txt | 69 +++++++++++++++++++++++ 2 files changed, 71 insertions(+) create mode 100644 Documentation/filesystems/nfs/fault_injection.txt (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/nfs/00-INDEX b/Documentation/filesystems/nfs/00-INDEX index a57e12411d2a..1716874a651e 100644 --- a/Documentation/filesystems/nfs/00-INDEX +++ b/Documentation/filesystems/nfs/00-INDEX @@ -2,6 +2,8 @@ - this file (nfs-related documentation). Exporting - explanation of how to make filesystems exportable. +fault_injection.txt + - information for using fault injection on the server knfsd-stats.txt - statistics which the NFS server makes available to user space. nfs.txt diff --git a/Documentation/filesystems/nfs/fault_injection.txt b/Documentation/filesystems/nfs/fault_injection.txt new file mode 100644 index 000000000000..426d166089a3 --- /dev/null +++ b/Documentation/filesystems/nfs/fault_injection.txt @@ -0,0 +1,69 @@ + +Fault Injection +=============== +Fault injection is a method for forcing errors that may not normally occur, or +may be difficult to reproduce. Forcing these errors in a controlled environment +can help the developer find and fix bugs before their code is shipped in a +production system. Injecting an error on the Linux NFS server will allow us to +observe how the client reacts and if it manages to recover its state correctly. + +NFSD_FAULT_INJECTION must be selected when configuring the kernel to use this +feature. + + +Using Fault Injection +===================== +On the client, mount the fault injection server through NFS v4.0+ and do some +work over NFS (open files, take locks, ...). + +On the server, mount the debugfs filesystem to and ls +/nfsd. This will show a list of files that will be used for +injecting faults on the NFS server. As root, write a number n to the file +corresponding to the action you want the server to take. The server will then +process the first n items it finds. So if you want to forget 5 locks, echo '5' +to /nfsd/forget_locks. A value of 0 will tell the server to forget +all corresponding items. A log message will be created containing the number +of items forgotten (check dmesg). + +Go back to work on the client and check if the client recovered from the error +correctly. + + +Available Faults +================ +forget_clients: + The NFS server keeps a list of clients that have placed a mount call. If + this list is cleared, the server will have no knowledge of who the client + is, forcing the client to reauthenticate with the server. + +forget_openowners: + The NFS server keeps a list of what files are currently opened and who + they were opened by. Clearing this list will force the client to reopen + its files. + +forget_locks: + The NFS server keeps a list of what files are currently locked in the VFS. + Clearing this list will force the client to reclaim its locks (files are + unlocked through the VFS as they are cleared from this list). + +forget_delegations: + A delegation is used to assure the client that a file, or part of a file, + has not changed since the delegation was awarded. Clearing this list will + force the client to reaquire its delegation before accessing the file + again. + +recall_delegations: + Delegations can be recalled by the server when another client attempts to + access a file. This test will notify the client that its delegation has + been revoked, forcing the client to reaquire the delegation before using + the file again. + + +tools/nfs/inject_faults.sh script +================================= +This script has been created to ease the fault injection process. This script +will detect the mounted debugfs directory and write to the files located there +based on the arguments passed by the user. For example, running +`inject_faults.sh forget_locks 1` as root will instruct the server to forget +one lock. Running `inject_faults forget_locks` will instruct the server to +forgetall locks. -- cgit v1.2.3 From 89cab5b5727d3139adc247e3a3d4ee5b10e3eda5 Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Thu, 29 Dec 2011 13:54:17 +0000 Subject: Squashfs: Update documentation to include xattrs One paragraph was not updated when xattrs were added to Squashfs. Signed-off-by: Phillip Lougher --- Documentation/filesystems/squashfs.txt | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt index 7db3ebda5a4c..403c090aca39 100644 --- a/Documentation/filesystems/squashfs.txt +++ b/Documentation/filesystems/squashfs.txt @@ -93,8 +93,8 @@ byte alignment: Compressed data blocks are written to the filesystem as files are read from the source directory, and checked for duplicates. Once all file data has been -written the completed inode, directory, fragment, export and uid/gid lookup -tables are written. +written the completed inode, directory, fragment, export, uid/gid lookup and +xattr tables are written. 3.1 Compression options ----------------------- @@ -151,7 +151,7 @@ in each metadata block. Directories are sorted in alphabetical order, and at lookup the index is scanned linearly looking for the first filename alphabetically larger than the filename being looked up. At this point the location of the metadata block the filename is in has been found. -The general idea of the index is ensure only one metadata block needs to be +The general idea of the index is to ensure only one metadata block needs to be decompressed to do a lookup irrespective of the length of the directory. This scheme has the advantage that it doesn't require extra memory overhead and doesn't require much extra storage on disk. -- cgit v1.2.3 From a40dc6cc2e121abcbd1b22583ef5447763df510c Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Tue, 10 Jan 2012 09:12:55 -0800 Subject: ceph: enable/disable dentry complete flags via mount option Enable/disable use of the dentry dir 'complete' flag via a mount option. This lets the admin control whether ceph uses the dcache to satisfy negative lookups or readdir when it has the entire directory contents in its cache. This is purely a performance optimization; correctness is guaranteed whether it is enabled or not. Reviewed-by: Christoph Hellwig Signed-off-by: Sage Weil --- Documentation/filesystems/ceph.txt | 18 +++++++++++++----- fs/ceph/dir.c | 25 ++++++++++++++++++++++--- fs/ceph/super.c | 14 ++++++++++++++ fs/ceph/super.h | 1 + 4 files changed, 50 insertions(+), 8 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/ceph.txt b/Documentation/filesystems/ceph.txt index 763d8ebbbebd..d6030aa33376 100644 --- a/Documentation/filesystems/ceph.txt +++ b/Documentation/filesystems/ceph.txt @@ -119,12 +119,20 @@ Mount Options must rely on TCP's error correction to detect data corruption in the data payload. - noasyncreaddir - Disable client's use its local cache to satisfy readdir - requests. (This does not change correctness; the client uses - cached metadata only when a lease or capability ensures it is - valid.) + dcache + Use the dcache contents to perform negative lookups and + readdir when the client has the entire directory contents in + its cache. (This does not change correctness; the client uses + cached metadata only when a lease or capability ensures it is + valid.) + + nodcache + Do not use the dcache as above. This avoids a significant amount of + complex code, sacrificing performance without affecting correctness, + and is useful for tracking down bugs. + noasyncreaddir + Do not use the dcache as above for readdir. More Information ================ diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 974ef1e4d268..5259abfb5dd9 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -1094,17 +1094,36 @@ static int ceph_snapdir_d_revalidate(struct dentry *dentry, */ void ceph_dir_set_complete(struct inode *inode) { - /* not yet implemented */ + struct dentry *dentry = d_find_any_alias(inode); + + if (dentry && ceph_dentry(dentry) && + ceph_test_mount_opt(ceph_sb_to_client(dentry->d_sb), DCACHE)) { + dout(" marking %p (%p) complete\n", inode, dentry); + set_bit(CEPH_D_COMPLETE, &ceph_dentry(dentry)->flags); + } + dput(dentry); } void ceph_dir_clear_complete(struct inode *inode) { - /* not yet implemented */ + struct dentry *dentry = d_find_any_alias(inode); + + if (dentry && ceph_dentry(dentry)) { + dout(" marking %p (%p) complete\n", inode, dentry); + set_bit(CEPH_D_COMPLETE, &ceph_dentry(dentry)->flags); + } + dput(dentry); } bool ceph_dir_test_complete(struct inode *inode) { - /* not yet implemented */ + struct dentry *dentry = d_find_any_alias(inode); + + if (dentry && ceph_dentry(dentry)) { + dout(" marking %p (%p) NOT complete\n", inode, dentry); + clear_bit(CEPH_D_COMPLETE, &ceph_dentry(dentry)->flags); + } + dput(dentry); return false; } diff --git a/fs/ceph/super.c b/fs/ceph/super.c index ec74313e901f..9c62fe02ce05 100644 --- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -131,6 +131,8 @@ enum { Opt_rbytes, Opt_norbytes, Opt_noasyncreaddir, + Opt_dcache, + Opt_nodcache, Opt_ino32, }; @@ -152,6 +154,8 @@ static match_table_t fsopt_tokens = { {Opt_rbytes, "rbytes"}, {Opt_norbytes, "norbytes"}, {Opt_noasyncreaddir, "noasyncreaddir"}, + {Opt_dcache, "dcache"}, + {Opt_nodcache, "nodcache"}, {Opt_ino32, "ino32"}, {-1, NULL} }; @@ -231,6 +235,12 @@ static int parse_fsopt_token(char *c, void *private) case Opt_noasyncreaddir: fsopt->flags |= CEPH_MOUNT_OPT_NOASYNCREADDIR; break; + case Opt_dcache: + fsopt->flags |= CEPH_MOUNT_OPT_DCACHE; + break; + case Opt_nodcache: + fsopt->flags &= ~CEPH_MOUNT_OPT_DCACHE; + break; case Opt_ino32: fsopt->flags |= CEPH_MOUNT_OPT_INO32; break; @@ -377,6 +387,10 @@ static int ceph_show_options(struct seq_file *m, struct vfsmount *mnt) seq_puts(m, ",norbytes"); if (fsopt->flags & CEPH_MOUNT_OPT_NOASYNCREADDIR) seq_puts(m, ",noasyncreaddir"); + if (fsopt->flags & CEPH_MOUNT_OPT_DCACHE) + seq_puts(m, ",dcache"); + else + seq_puts(m, ",nodcache"); if (fsopt->wsize) seq_printf(m, ",wsize=%d", fsopt->wsize); diff --git a/fs/ceph/super.h b/fs/ceph/super.h index edcbf3774a56..140f99f978c4 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -28,6 +28,7 @@ #define CEPH_MOUNT_OPT_RBYTES (1<<5) /* dir st_bytes = rbytes */ #define CEPH_MOUNT_OPT_NOASYNCREADDIR (1<<7) /* no dcache readdir */ #define CEPH_MOUNT_OPT_INO32 (1<<8) /* 32 bit inos */ +#define CEPH_MOUNT_OPT_DCACHE (1<<9) /* use dcache for readdir etc */ #define CEPH_MOUNT_OPT_DEFAULT (CEPH_MOUNT_OPT_RBYTES) -- cgit v1.2.3