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| author | William Cohen <wcohen@redhat.com> | 2010-03-01 15:39:23 -0500 |
|---|---|---|
| committer | William Cohen <wcohen@redhat.com> | 2010-03-02 11:52:20 -0500 |
| commit | 1f95aa31dd8859031149678651916e2441a8d3c5 (patch) | |
| tree | 8f83fcb48cbc98ba1834a9f91a39c818a6d28404 /doc | |
| parent | bfbbb76e5d0294cc1d44f42ab6c2d91149067b6c (diff) | |
| download | systemtap-steved-1f95aa31dd8859031149678651916e2441a8d3c5.tar.gz systemtap-steved-1f95aa31dd8859031149678651916e2441a8d3c5.tar.xz systemtap-steved-1f95aa31dd8859031149678651916e2441a8d3c5.zip | |
Make the inode-watch.stp example work on newer kernels.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/tutorial.tex | 25 | ||||
| -rw-r--r-- | doc/tutorial/inode-watch.stp | 7 |
2 files changed, 22 insertions, 10 deletions
diff --git a/doc/tutorial.tex b/doc/tutorial.tex index 3a04900b..1200967b 100644 --- a/doc/tutorial.tex +++ b/doc/tutorial.tex @@ -427,13 +427,18 @@ Let's say that you are trying to trace filesystem reads/writes to a particular device/inode. From your knowledge of the kernel, you know that two functions of interest could be \verb+vfs_read+ and \verb+vfs_write+. Each takes a \verb+struct file *+ argument, inside -which there is a \verb+struct dentry *+, a \verb+struct inode *+, and -so on. Systemtap allows limited dereferencing of such pointer chains. +there is either a \verb+struct dentry *+ or \verb+struct path *+ which +has a \verb+struct dentry *+. +The \verb+struct dentry *+ contains a \verb+struct inode *+, and +so on. +Systemtap allows limited dereferencing of such pointer chains. Two functions, \verb+user_string+ and \verb+kernel_string+, can copy \verb+char *+ target variables into systemtap strings. Figure~\ref{fig:inode-watch} demonstrates one way to monitor a -particular file (identifed by device number and inode number). This -example also demonstrates pasting numeric command-line arguments +particular file (identifed by device number and inode number). +The script selects the appropriate variants of \verb+dev_nr+ +and\verb+inode_nr+ based on the kernel version. +This example also demonstrates pasting numeric command-line arguments (\verb+$1+ etc.) into scripts. %$ @@ -444,8 +449,13 @@ example also demonstrates pasting numeric command-line arguments probe kernel.function ("vfs_write"), kernel.function ("vfs_read") { +%( kernel_v >= "2.6.20" %? + dev_nr = $file->f_path->dentry->d_inode->i_sb->s_dev + inode_nr = $file->f_path->dentry->d_inode->i_ino +%: dev_nr = $file->f_dentry->d_inode->i_sb->s_dev inode_nr = $file->f_dentry->d_inode->i_ino +%) if (dev_nr == ($1 << 20 | $2) # major/minor device && inode_nr == $3) @@ -453,11 +463,10 @@ probe kernel.function ("vfs_write"), execname(), pid(), probefunc(), dev_nr, inode_nr) } # stat -c '%D %i' /etc/crontab -803 988136 +fd03 133099 # stap inode-watch.stp 8 3 988136 -crond(2419) vfs_read 0x800003/988136 -crond(2419) vfs_read 0x800003/988136 -crond(2419) vfs_read 0x800003/988136 +more(30789) vfs_read 0xfd00003/133099 +more(30789) vfs_read 0xfd00003/133099 \end{verbatim} % $ \end{boxedminipage} diff --git a/doc/tutorial/inode-watch.stp b/doc/tutorial/inode-watch.stp index caf04b9a..2209f309 100644 --- a/doc/tutorial/inode-watch.stp +++ b/doc/tutorial/inode-watch.stp @@ -1,13 +1,16 @@ probe kernel.function ("vfs_write"), kernel.function ("vfs_read") { +%( kernel_v >= "2.6.20" %? + dev_nr = $file->f_path->dentry->d_inode->i_sb->s_dev + inode_nr = $file->f_path->dentry->d_inode->i_ino +%: dev_nr = $file->f_dentry->d_inode->i_sb->s_dev inode_nr = $file->f_dentry->d_inode->i_ino +%) if (dev_nr == ($1 << 20 | $2) # major/minor device && inode_nr == $3) printf ("%s(%d) %s 0x%x/%u\n", execname(), pid(), probefunc(), dev_nr, inode_nr) } - -# dev_name = kernel_string ($file->f_dentry->d_inode->i_sb->s_id) |